From 71f557355ddaea358c43b151de3a0e045aaa0863 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu@google.com>
Date: Sat, 7 Jan 2023 20:02:20 -0800
Subject: [PATCH] [clang-tools-extra] Add #include <optional> (NFC)

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
---
 .../clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp   | 1 +
 clang-tools-extra/clang-doc/HTMLGenerator.cpp                    | 1 +
 .../clang-include-fixer/find-all-symbols/FindAllMacros.cpp       | 1 +
 .../clang-include-fixer/find-all-symbols/FindAllMacros.h         | 1 +
 .../clang-include-fixer/find-all-symbols/FindAllSymbols.cpp      | 1 +
 clang-tools-extra/clang-query/Query.cpp                          | 1 +
 clang-tools-extra/clang-query/QueryParser.cpp                    | 1 +
 clang-tools-extra/clang-query/tool/ClangQuery.cpp                | 1 +
 clang-tools-extra/clang-tidy/ClangTidyCheck.cpp                  | 1 +
 clang-tools-extra/clang-tidy/ClangTidyCheck.h                    | 1 +
 clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp     | 1 +
 clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h       | 1 +
 clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp | 1 +
 clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp          | 1 +
 clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp    | 1 +
 clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp  | 1 +
 .../clang-tidy/abseil/DurationConversionCastCheck.cpp            | 1 +
 .../clang-tidy/abseil/DurationFactoryFloatCheck.cpp              | 1 +
 .../clang-tidy/abseil/DurationFactoryScaleCheck.cpp              | 1 +
 clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp         | 1 +
 clang-tools-extra/clang-tidy/abseil/DurationRewriter.h           | 1 +
 clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp | 1 +
 .../clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp           | 1 +
 clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp      | 1 +
 clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp     | 1 +
 .../clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp           | 1 +
 .../clang-tidy/bugprone/BadSignalToKillThreadCheck.h             | 1 +
 .../clang-tidy/bugprone/EasilySwappableParametersCheck.cpp       | 1 +
 .../bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp     | 1 +
 .../bugprone/ImplicitWideningOfMultiplicationResultCheck.h       | 1 +
 .../clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp         | 1 +
 .../clang-tidy/bugprone/ReservedIdentifierCheck.cpp              | 1 +
 clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h  | 1 +
 clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp | 1 +
 .../clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp      | 1 +
 .../clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp         | 1 +
 .../clang-tidy/bugprone/UncheckedOptionalAccessCheck.h           | 1 +
 clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp      | 1 +
 .../clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp          | 1 +
 .../cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp       | 1 +
 .../clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp | 1 +
 .../clang-tidy/google/UpgradeGoogletestCaseCheck.cpp             | 1 +
 clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp   | 1 +
 clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp          | 1 +
 .../clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp       | 1 +
 clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp      | 1 +
 clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp      | 1 +
 .../modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp         | 1 +
 clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp | 1 +
 .../clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp          | 1 +
 .../clang-tidy/modernize/UseTrailingReturnTypeCheck.h            | 1 +
 clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h              | 1 +
 clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h             | 1 +
 .../clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp        | 1 +
 .../clang-tidy/performance/FasterStringFindCheck.cpp             | 1 +
 clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp   | 1 +
 .../clang-tidy/performance/UnnecessaryCopyInitialization.cpp     | 1 +
 .../clang-tidy/performance/UnnecessaryValueParamCheck.cpp        | 1 +
 .../clang-tidy/readability/ConstReturnTypeCheck.cpp              | 1 +
 .../clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp  | 1 +
 .../clang-tidy/readability/IdentifierNamingCheck.cpp             | 1 +
 clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h | 1 +
 .../clang-tidy/readability/IsolateDeclarationCheck.cpp           | 1 +
 .../clang-tidy/readability/NamespaceCommentCheck.cpp             | 1 +
 clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp  | 1 +
 .../clang-tidy/readability/RedundantStringInitCheck.cpp          | 1 +
 .../clang-tidy/readability/SimplifyBooleanExprCheck.cpp          | 1 +
 .../clang-tidy/readability/SuspiciousCallArgumentCheck.cpp       | 1 +
 .../clang-tidy/readability/SuspiciousCallArgumentCheck.h         | 1 +
 .../clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp       | 1 +
 clang-tools-extra/clang-tidy/utils/ExprSequence.cpp              | 1 +
 clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp       | 1 +
 clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h         | 1 +
 clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp            | 1 +
 clang-tools-extra/clang-tidy/utils/FixItHintUtils.h              | 1 +
 clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp           | 1 +
 clang-tools-extra/clang-tidy/utils/IncludeInserter.h             | 1 +
 clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp             | 1 +
 clang-tools-extra/clang-tidy/utils/IncludeSorter.h               | 1 +
 clang-tools-extra/clang-tidy/utils/LexerUtils.cpp                | 1 +
 clang-tools-extra/clang-tidy/utils/LexerUtils.h                  | 1 +
 clang-tools-extra/clang-tidy/utils/Matchers.h                    | 1 +
 clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp          | 1 +
 clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h            | 1 +
 clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp     | 1 +
 clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h       | 1 +
 clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp | 1 +
 clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h   | 1 +
 clang-tools-extra/clang-tidy/utils/TypeTraits.cpp                | 1 +
 clang-tools-extra/clang-tidy/utils/TypeTraits.h                  | 1 +
 clang-tools-extra/clang-tidy/utils/UsingInserter.cpp             | 1 +
 clang-tools-extra/clang-tidy/utils/UsingInserter.h               | 1 +
 clang-tools-extra/clangd/AST.cpp                                 | 1 +
 clang-tools-extra/clangd/AST.h                                   | 1 +
 clang-tools-extra/clangd/ClangdLSPServer.cpp                     | 1 +
 clang-tools-extra/clangd/ClangdLSPServer.h                       | 1 +
 clang-tools-extra/clangd/ClangdServer.cpp                        | 1 +
 clang-tools-extra/clangd/ClangdServer.h                          | 1 +
 clang-tools-extra/clangd/CodeComplete.cpp                        | 1 +
 clang-tools-extra/clangd/CodeComplete.h                          | 1 +
 clang-tools-extra/clangd/CompileCommands.h                       | 1 +
 clang-tools-extra/clangd/ConfigCompile.cpp                       | 1 +
 clang-tools-extra/clangd/Diagnostics.cpp                         | 1 +
 clang-tools-extra/clangd/Diagnostics.h                           | 1 +
 clang-tools-extra/clangd/DraftStore.cpp                          | 1 +
 clang-tools-extra/clangd/DraftStore.h                            | 1 +
 clang-tools-extra/clangd/DumpAST.cpp                             | 1 +
 clang-tools-extra/clangd/ExpectedTypes.cpp                       | 1 +
 clang-tools-extra/clangd/ExpectedTypes.h                         | 1 +
 clang-tools-extra/clangd/FS.cpp                                  | 1 +
 clang-tools-extra/clangd/FS.h                                    | 1 +
 clang-tools-extra/clangd/FeatureModule.h                         | 1 +
 clang-tools-extra/clangd/FindSymbols.cpp                         | 1 +
 clang-tools-extra/clangd/GlobalCompilationDatabase.cpp           | 1 +
 clang-tools-extra/clangd/GlobalCompilationDatabase.h             | 1 +
 clang-tools-extra/clangd/HeaderSourceSwitch.cpp                  | 1 +
 clang-tools-extra/clangd/HeaderSourceSwitch.h                    | 1 +
 clang-tools-extra/clangd/Headers.cpp                             | 1 +
 clang-tools-extra/clangd/Headers.h                               | 1 +
 clang-tools-extra/clangd/Hover.cpp                               | 1 +
 clang-tools-extra/clangd/Hover.h                                 | 1 +
 clang-tools-extra/clangd/IncludeCleaner.cpp                      | 1 +
 clang-tools-extra/clangd/IncludeCleaner.h                        | 1 +
 clang-tools-extra/clangd/IncludeFixer.cpp                        | 1 +
 clang-tools-extra/clangd/IncludeFixer.h                          | 1 +
 clang-tools-extra/clangd/InlayHints.cpp                          | 1 +
 clang-tools-extra/clangd/JSONTransport.cpp                       | 1 +
 clang-tools-extra/clangd/ParsedAST.cpp                           | 1 +
 clang-tools-extra/clangd/ParsedAST.h                             | 1 +
 clang-tools-extra/clangd/Protocol.h                              | 1 +
 clang-tools-extra/clangd/Quality.cpp                             | 1 +
 clang-tools-extra/clangd/Quality.h                               | 1 +
 clang-tools-extra/clangd/Selection.cpp                           | 1 +
 clang-tools-extra/clangd/SemanticHighlighting.cpp                | 1 +
 clang-tools-extra/clangd/SemanticSelection.cpp                   | 1 +
 clang-tools-extra/clangd/SourceCode.cpp                          | 1 +
 clang-tools-extra/clangd/SourceCode.h                            | 1 +
 clang-tools-extra/clangd/SystemIncludeExtractor.cpp              | 1 +
 clang-tools-extra/clangd/TUScheduler.cpp                         | 1 +
 clang-tools-extra/clangd/TUScheduler.h                           | 1 +
 clang-tools-extra/clangd/XRefs.cpp                               | 1 +
 clang-tools-extra/clangd/XRefs.h                                 | 1 +
 clang-tools-extra/clangd/index/Background.cpp                    | 1 +
 clang-tools-extra/clangd/index/Background.h                      | 1 +
 clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp        | 1 +
 clang-tools-extra/clangd/index/BackgroundQueue.cpp               | 1 +
 clang-tools-extra/clangd/index/FileIndex.cpp                     | 1 +
 clang-tools-extra/clangd/index/FileIndex.h                       | 1 +
 clang-tools-extra/clangd/index/Index.h                           | 1 +
 clang-tools-extra/clangd/index/IndexAction.cpp                   | 1 +
 clang-tools-extra/clangd/index/Serialization.h                   | 1 +
 clang-tools-extra/clangd/index/StdLib.cpp                        | 1 +
 clang-tools-extra/clangd/index/StdLib.h                          | 1 +
 clang-tools-extra/clangd/index/SymbolCollector.cpp               | 1 +
 clang-tools-extra/clangd/index/SymbolCollector.h                 | 1 +
 clang-tools-extra/clangd/index/YAMLSerialization.cpp             | 1 +
 clang-tools-extra/clangd/index/dex/Dex.cpp                       | 1 +
 clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp                 | 1 +
 clang-tools-extra/clangd/index/remote/server/Server.cpp          | 1 +
 clang-tools-extra/clangd/refactor/InsertionPoint.cpp             | 1 +
 clang-tools-extra/clangd/refactor/Rename.cpp                     | 1 +
 clang-tools-extra/clangd/refactor/Rename.h                       | 1 +
 clang-tools-extra/clangd/refactor/Tweak.h                        | 1 +
 clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp        | 1 +
 clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp       | 1 +
 clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp             | 1 +
 clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp      | 1 +
 clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp     | 1 +
 .../clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp         | 1 +
 .../clangd/refactor/tweaks/RemoveUsingNamespace.cpp              | 1 +
 clang-tools-extra/clangd/tool/Check.cpp                          | 1 +
 clang-tools-extra/clangd/tool/ClangdMain.cpp                     | 1 +
 clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp      | 1 +
 clang-tools-extra/clangd/unittests/ClangdTests.cpp               | 1 +
 clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp        | 1 +
 clang-tools-extra/clangd/unittests/ConfigTesting.h               | 1 +
 clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp          | 1 +
 .../clangd/unittests/GlobalCompilationDatabaseTests.cpp          | 1 +
 clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp   | 1 +
 clang-tools-extra/clangd/unittests/HeadersTests.cpp              | 1 +
 clang-tools-extra/clangd/unittests/LSPBinderTests.cpp            | 1 +
 clang-tools-extra/clangd/unittests/LSPClient.cpp                 | 1 +
 clang-tools-extra/clangd/unittests/PreambleTests.cpp             | 1 +
 clang-tools-extra/clangd/unittests/SourceCodeTests.cpp           | 1 +
 clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp      | 1 +
 clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp           | 1 +
 clang-tools-extra/clangd/unittests/SyncAPI.cpp                   | 1 +
 clang-tools-extra/clangd/unittests/SyncAPI.h                     | 1 +
 clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp          | 1 +
 clang-tools-extra/clangd/unittests/TestFS.cpp                    | 1 +
 clang-tools-extra/clangd/unittests/TestFS.h                      | 1 +
 clang-tools-extra/clangd/unittests/TestWorkspace.cpp             | 1 +
 clang-tools-extra/clangd/unittests/TestWorkspace.h               | 1 +
 clang-tools-extra/clangd/unittests/XRefsTests.cpp                | 1 +
 clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp    | 1 +
 clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp       | 1 +
 clang-tools-extra/clangd/xpc/XPCTransport.cpp                    | 1 +
 clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h    | 1 +
 clang-tools-extra/pseudo/lib/DirectiveTree.cpp                   | 1 +
 clang-tools-extra/pseudo/lib/Forest.cpp                          | 1 +
 clang-tools-extra/pseudo/lib/GLR.cpp                             | 1 +
 clang-tools-extra/pseudo/tool/ClangPseudo.cpp                    | 1 +
 clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp          | 1 +
 clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp  | 1 +
 clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp        | 1 +
 .../unittests/clang-tidy/TransformerClangTidyCheckTest.cpp       | 1 +
 206 files changed, 206 insertions(+)

diff --git a/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp b/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
index b9e83aca0ab9..43ecfd8f0ccc 100644
--- a/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
+++ b/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
@@ -29,6 +29,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang-tools-extra/clang-doc/HTMLGenerator.cpp b/clang-tools-extra/clang-doc/HTMLGenerator.cpp
index 37598c43e957..589a3232c90c 100644
--- a/clang-tools-extra/clang-doc/HTMLGenerator.cpp
+++ b/clang-tools-extra/clang-doc/HTMLGenerator.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <string>
 
 using namespace llvm;
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
index f41d478293b9..2cee43845aaa 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
@@ -16,6 +16,7 @@
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/Token.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace find_all_symbols {
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
index 0a51ab192e8d..99a7f5deccdc 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
@@ -13,6 +13,7 @@
 #include "SymbolInfo.h"
 #include "SymbolReporter.h"
 #include "clang/Lex/PPCallbacks.h"
+#include <optional>
 
 namespace clang {
 class MacroInfo;
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
index ccfdb9332c44..8608ba74ce9f 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
@@ -18,6 +18,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/FileSystem.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-query/Query.cpp b/clang-tools-extra/clang-query/Query.cpp
index 4d62f37231b7..d1db851c1297 100644
--- a/clang-tools-extra/clang-query/Query.cpp
+++ b/clang-tools-extra/clang-query/Query.cpp
@@ -14,6 +14,7 @@
 #include "clang/Frontend/TextDiagnostic.h"
 #include "clang/Tooling/NodeIntrospection.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::dynamic;
diff --git a/clang-tools-extra/clang-query/QueryParser.cpp b/clang-tools-extra/clang-query/QueryParser.cpp
index b80ad04726bc..77621d252aed 100644
--- a/clang-tools-extra/clang-query/QueryParser.cpp
+++ b/clang-tools-extra/clang-query/QueryParser.cpp
@@ -14,6 +14,7 @@
 #include "clang/Tooling/NodeIntrospection.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 #include <set>
 
 using namespace llvm;
diff --git a/clang-tools-extra/clang-query/tool/ClangQuery.cpp b/clang-tools-extra/clang-query/tool/ClangQuery.cpp
index 2bdb36192f35..6ba2b1a4412d 100644
--- a/clang-tools-extra/clang-query/tool/ClangQuery.cpp
+++ b/clang-tools-extra/clang-query/tool/ClangQuery.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/WithColor.h"
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
index fedf3aa27169..8f90becf8ab2 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/YAMLParser.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/ClangTidyCheck.h b/clang-tools-extra/clang-tidy/ClangTidyCheck.h
index e5d98b0196f5..f2486eab5dfa 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <type_traits>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
index e6b907038a7e..05ca2573dc4e 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
@@ -36,6 +36,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Regex.h"
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
index 261e4f7ac862..475f38d334ca 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
@@ -17,6 +17,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Regex.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
index 9df26411060c..0cfdda3b5ded 100644
--- a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
+++ b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
@@ -12,6 +12,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Serialization/ASTReader.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
index 08d837c105c8..7a822cd55bed 100644
--- a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
+++ b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
@@ -28,6 +28,7 @@
 #include <cassert>
 #include <cstddef>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <type_traits>
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
index 60047096e534..585b7c1310e2 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
index a6e12dd8966b..39c7ba4fc9b4 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
index d3007d79f376..3a83e6707efc 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
index 4b0ef1b3f4ee..09512347acca 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
index ba7dc70b2f60..b33f1e364a66 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
index 43f8ed709651..c2325c11e2ad 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <cmath>
+#include <optional>
 
 #include "DurationRewriter.h"
 #include "clang/Tooling/FixIt.h"
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
index d8b0acf63cfd..a23dfaf9bcef 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
+++ b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include <cinttypes>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
index 322171444e6d..4d12fd337ace 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
index b73b1002763c..36e670ea8c36 100644
--- a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
index 391f38f165c3..ddbde758684f 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
index 58ce1f4be622..9f2fba454cbd 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
index f1bfcc84c95f..2676540ab2c5 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
index 6276179d76a0..3a5919d5121a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_BADSIGNALTOKILLTHREADCHECK_H
 
 #include "../ClangTidyCheck.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
index f1b78883aece..23244dceefda 100644
--- a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
@@ -16,6 +16,7 @@
 
 #define DEBUG_TYPE "EasilySwappableParametersCheck"
 #include "llvm/Support/Debug.h"
+#include <optional>
 
 namespace optutils = clang::tidy::utils::options;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
index fbf3438889ef..601949bfb16a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -9,6 +9,7 @@
 #include "ImplicitWideningOfMultiplicationResultCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
index 19c364d92785..74152efa4736 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "../utils/IncludeInserter.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
index 17537f1d1f86..ce58f1e50f0e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -13,6 +13,7 @@
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
index 71c7daaf7c1e..560e9a157b46 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
@@ -14,6 +14,7 @@
 #include "clang/Lex/Token.h"
 #include <algorithm>
 #include <cctype>
+#include <optional>
 
 // FixItHint
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
index 0769fcea5f23..99c1dbe3363e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
@@ -11,6 +11,7 @@
 
 #include "../utils/RenamerClangTidyCheck.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
index cd9aa00079e1..177882777f07 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
@@ -9,6 +9,7 @@
 #include "SuspiciousIncludeCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
index d731d7d16962..a1d04dc966ad 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
@@ -9,6 +9,7 @@
 #include "SuspiciousMemoryComparisonCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
index ccf936594019..89d39d289816 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Error.h"
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
index ae583fd0e940..052d6c6d5a6c 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
@@ -12,6 +12,7 @@
 #include "../ClangTidyCheck.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
index d2a0dd66d323..6c4fa9c55609 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/STLExtras.h"
 
 #include "../utils/ExprSequence.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils;
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
index e54a4f35fd11..d75990823ce5 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
index c80be3df1ce6..6692baca99d5 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
index 2eb6e40d9863..234ddd4ae936 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 #include <string>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
index f5ab332ff46a..1055d26e534c 100644
--- a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
index e7c79331757a..7c3811ceb4da 100644
--- a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -25,6 +25,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
index 93df4915e9f7..eaa7022321f9 100644
--- a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
+#include <optional>
 #include <string>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
index 5e3e05e88f0c..900077ee87b8 100644
--- a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
@@ -9,6 +9,7 @@
 #include "DeprecatedIosBaseAliasesCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
index 3033fcbd3ee4..2db958ce8e69 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstring>
+#include <optional>
 #include <utility>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
index fc3dfbdeac78..7253b1daf6ae 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
@@ -21,6 +21,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
index 438fd4882b7f..fd96cb2ede97 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
index a545fae26a3b..adf070866893 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
index 9dc90937d6e5..6023fddb75ad 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/StringExtras.h"
 
 #include <cctype>
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
index c2d831089d7c..fa9dd407233d 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "clang/Lex/Token.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
index a8da911957ca..676654c2c271 100644
--- a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
+++ b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "clang/StaticAnalyzer/Checkers/MPIFunctionClassifier.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
index da7b7c289b46..261fec40160b 100644
--- a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
+++ b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
@@ -12,6 +12,7 @@
 #include "../ClangTidyCheck.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/StaticAnalyzer/Checkers/MPIFunctionClassifier.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
index 1650563a9693..5127eaa55795 100644
--- a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
@@ -25,6 +25,7 @@
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
index e16be632d742..190524720949 100644
--- a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
index 8046301e3ce7..d2899852bf13 100644
--- a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
@@ -14,6 +14,7 @@
 #include "../utils/TypeTraits.h"
 #include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 #include "clang/Basic/Diagnostic.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
index b76f4bb6973f..249c00265da9 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -14,6 +14,7 @@
 #include "../utils/OptionsUtils.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/Diagnostic.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
index a8ca761d435f..c3f742e06d09 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -16,6 +16,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
index 0c9bda79006f..e1ad21aaa3ab 100644
--- a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
@@ -13,6 +13,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
index ba9e3d8e7258..416952cda806 100644
--- a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <array>
 #include <cassert>
+#include <optional>
 #include <stack>
 #include <tuple>
 #include <type_traits>
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
index 524cd9010527..6aaa46d1c787 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/YAMLParser.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
index 2739d18a0f74..a3ff2d55fa77 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
@@ -11,6 +11,7 @@
 
 #include "../utils/RenamerClangTidyCheck.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 namespace clang {
 namespace tidy {
 namespace readability {
diff --git a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
index 45f3ea6c6812..bc3d40db1c6d 100644
--- a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
@@ -9,6 +9,7 @@
 #include "IsolateDeclarationCheck.h"
 #include "../utils/LexerUtils.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils::lexer;
diff --git a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
index 7ee48389c3c1..c53565c26040 100644
--- a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
@@ -14,6 +14,7 @@
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/StringExtras.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
index e25d1474ffdd..c2ec9312bd70 100644
--- a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
index d1537eba99f7..de250bbc6ce9 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
@@ -10,6 +10,7 @@
 #include "../utils/Matchers.h"
 #include "../utils/OptionsUtils.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
diff --git a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
index 1f1d605175a3..5e96a4917b07 100644
--- a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/SaveAndRestore.h"
 
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
index 2a5e614584fb..8272a550249d 100644
--- a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 #include <sstream>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
index dce19240e725..698d9cf52c1c 100644
--- a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "llvm/ADT/StringSet.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
index ee760f7c1ade..e6fe75799c32 100644
--- a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallString.h"
 #include <cctype>
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
index 1d7c11f20361..3ca854dba67f 100644
--- a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
@@ -8,6 +8,7 @@
 
 #include "ExprSequence.h"
 #include "clang/AST/ParentMapContext.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
index 07c9eb0f0098..6b1fe062fdd7 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
@@ -9,6 +9,7 @@
 #include "FileExtensionsUtils.h"
 #include "clang/Basic/CharInfo.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
index 26184a573783..a79cf9a45a12 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
index 546efd5ce5a2..2e96f29ffb45 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
@@ -10,6 +10,7 @@
 #include "LexerUtils.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
index 2f5a74153f89..ec2ed50d9c7d 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
 #include "clang/Sema/DeclSpec.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
index f4ca2d9129d7..ced2a73aa768 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
@@ -10,6 +10,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/Token.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeInserter.h b/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
index 8e7c5f76ff80..0f4ba11acb05 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
+++ b/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
@@ -13,6 +13,7 @@
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/StringSet.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 class Preprocessor;
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
index fc26d966c88e..5b25d10d031a 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeSorter.h b/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
index ac76fcd8d7d1..21fe5e48219c 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
+++ b/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_INCLUDESORTER_H
 
 #include "../ClangTidyCheck.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
index 6ab48afc7d20..8bdbc1d19b9a 100644
--- a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
@@ -9,6 +9,7 @@
 #include "LexerUtils.h"
 #include "clang/AST/AST.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/LexerUtils.h b/clang-tools-extra/clang-tidy/utils/LexerUtils.h
index b8e0f6ae2f7f..f67e0cb96ea9 100644
--- a/clang-tools-extra/clang-tidy/utils/LexerUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/LexerUtils.h
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang-tools-extra/clang-tidy/utils/Matchers.h b/clang-tools-extra/clang-tidy/utils/Matchers.h
index ad9e25f201ed..5a0e4599abf9 100644
--- a/clang-tools-extra/clang-tidy/utils/Matchers.h
+++ b/clang-tools-extra/clang-tidy/utils/Matchers.h
@@ -11,6 +11,7 @@
 
 #include "TypeTraits.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
index fcefdc32024c..71a06f8e8e66 100644
--- a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 namespace clang {
 namespace tidy {
 namespace utils {
diff --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
index 177b0980c745..934ce1341dc9 100644
--- a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
@@ -16,6 +16,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
 #include <map>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
index 449b0569537c..80a500592333 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
@@ -16,6 +16,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/PointerIntPair.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
index 327d98fc0485..2f3b79e73a1c 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
index 136b616836f1..b5e4b2b74a32 100644
--- a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/DiagnosticIDs.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
index c52fce5aa8fe..8ba15297cd95 100644
--- a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "IncludeSorter.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/Transformer/Transformer.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
index ef897da98146..70a6ca17769f 100644
--- a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TypeTraits.h b/clang-tools-extra/clang-tidy/utils/TypeTraits.h
index 7e6b795e8127..37db6ef24e8e 100644
--- a/clang-tools-extra/clang-tidy/utils/TypeTraits.h
+++ b/clang-tools-extra/clang-tidy/utils/TypeTraits.h
@@ -11,6 +11,7 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
index 480612c9140c..2a10d99c0dba 100644
--- a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/UsingInserter.h b/clang-tools-extra/clang-tidy/utils/UsingInserter.h
index dfdf5ed3488c..b23025bd5a78 100644
--- a/clang-tools-extra/clang-tidy/utils/UsingInserter.h
+++ b/clang-tools-extra/clang-tidy/utils/UsingInserter.h
@@ -13,6 +13,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 #include <set>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/AST.cpp b/clang-tools-extra/clangd/AST.cpp
index b9c76076f490..d33960a0f5cf 100644
--- a/clang-tools-extra/clangd/AST.cpp
+++ b/clang-tools-extra/clangd/AST.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 #include <iterator>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/AST.h b/clang-tools-extra/clangd/AST.h
index 738d1b3094ae..fbbee899d0ed 100644
--- a/clang-tools-extra/clangd/AST.h
+++ b/clang-tools-extra/clangd/AST.h
@@ -21,6 +21,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/MacroInfo.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp b/clang-tools-extra/clangd/ClangdLSPServer.cpp
index 8f5c8fa70242..7d7517679f9d 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -44,6 +44,7 @@
 #include <functional>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.h b/clang-tools-extra/clangd/ClangdLSPServer.h
index 43b5e748075d..1b1f4ad848fa 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.h
+++ b/clang-tools-extra/clangd/ClangdLSPServer.h
@@ -23,6 +23,7 @@
 #include <chrono>
 #include <cstddef>
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
index 2bde2a9e463b..5a9b2edbffec 100644
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -50,6 +50,7 @@
 #include <future>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <type_traits>
 
diff --git a/clang-tools-extra/clangd/ClangdServer.h b/clang-tools-extra/clangd/ClangdServer.h
index 98c67b8ef23c..097fed134464 100644
--- a/clang-tools-extra/clangd/ClangdServer.h
+++ b/clang-tools-extra/clangd/ClangdServer.h
@@ -35,6 +35,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <functional>
 #include <memory>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index 9015be6cf7c8..42e6ef2bc231 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -70,6 +70,7 @@
 #include <algorithm>
 #include <iterator>
 #include <limits>
+#include <optional>
 #include <utility>
 
 // We log detailed candidate here if you run with -debug-only=codecomplete.
diff --git a/clang-tools-extra/clangd/CodeComplete.h b/clang-tools-extra/clangd/CodeComplete.h
index b661eac5987f..e88e9b3734b2 100644
--- a/clang-tools-extra/clangd/CodeComplete.h
+++ b/clang-tools-extra/clangd/CodeComplete.h
@@ -31,6 +31,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <functional>
 #include <future>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/CompileCommands.h b/clang-tools-extra/clangd/CompileCommands.h
index 3cf41afd4ccf..561d9ea2f9ed 100644
--- a/clang-tools-extra/clangd/CompileCommands.h
+++ b/clang-tools-extra/clangd/CompileCommands.h
@@ -13,6 +13,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <deque>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
index 2291e5fdaf75..e1a511d0a082 100644
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -45,6 +45,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Diagnostics.cpp b/clang-tools-extra/clangd/Diagnostics.cpp
index a6a0204cf6b7..6c8cf5c52217 100644
--- a/clang-tools-extra/clangd/Diagnostics.cpp
+++ b/clang-tools-extra/clangd/Diagnostics.cpp
@@ -33,6 +33,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Diagnostics.h b/clang-tools-extra/clangd/Diagnostics.h
index 6004bb147361..b1a1f0170d34 100644
--- a/clang-tools-extra/clangd/Diagnostics.h
+++ b/clang-tools-extra/clangd/Diagnostics.h
@@ -23,6 +23,7 @@
 #include <cassert>
 #include <functional>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/DraftStore.cpp b/clang-tools-extra/clangd/DraftStore.cpp
index 8f5b54bc7b21..7df70e69bdf3 100644
--- a/clang-tools-extra/clangd/DraftStore.cpp
+++ b/clang-tools-extra/clangd/DraftStore.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/DraftStore.h b/clang-tools-extra/clangd/DraftStore.h
index 9a4692621496..a19fe55890b1 100644
--- a/clang-tools-extra/clangd/DraftStore.h
+++ b/clang-tools-extra/clangd/DraftStore.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <mutex>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/DumpAST.cpp b/clang-tools-extra/clangd/DumpAST.cpp
index 1cf5e4ef8fe9..438733d44f13 100644
--- a/clang-tools-extra/clangd/DumpAST.cpp
+++ b/clang-tools-extra/clangd/DumpAST.cpp
@@ -23,6 +23,7 @@
 #include "clang/Tooling/Syntax/Tokens.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/ExpectedTypes.cpp b/clang-tools-extra/clangd/ExpectedTypes.cpp
index c45fa5925dbf..563612aa745c 100644
--- a/clang-tools-extra/clangd/ExpectedTypes.cpp
+++ b/clang-tools-extra/clangd/ExpectedTypes.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Index/USRGeneration.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/ExpectedTypes.h b/clang-tools-extra/clangd/ExpectedTypes.h
index 873b106b91d1..6cfd0936def6 100644
--- a/clang-tools-extra/clangd/ExpectedTypes.h
+++ b/clang-tools-extra/clangd/ExpectedTypes.h
@@ -20,6 +20,7 @@
 
 #include "clang/AST/Type.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 namespace clang {
 class CodeCompletionResult;
diff --git a/clang-tools-extra/clangd/FS.cpp b/clang-tools-extra/clangd/FS.cpp
index 089fbac13e32..587b9212188c 100644
--- a/clang-tools-extra/clangd/FS.cpp
+++ b/clang-tools-extra/clangd/FS.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/LLVM.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/FS.h b/clang-tools-extra/clangd/FS.h
index 5994bdff9271..96b04dc7c9e5 100644
--- a/clang-tools-extra/clangd/FS.h
+++ b/clang-tools-extra/clangd/FS.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/FeatureModule.h b/clang-tools-extra/clangd/FeatureModule.h
index 43007a297469..eb4232f26b06 100644
--- a/clang-tools-extra/clangd/FeatureModule.h
+++ b/clang-tools-extra/clangd/FeatureModule.h
@@ -16,6 +16,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/JSON.h"
 #include <memory>
+#include <optional>
 #include <type_traits>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/FindSymbols.cpp b/clang-tools-extra/clangd/FindSymbols.cpp
index 0a18d5b4528d..682ca79a746d 100644
--- a/clang-tools-extra/clangd/FindSymbols.cpp
+++ b/clang-tools-extra/clangd/FindSymbols.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include <limits>
+#include <optional>
 #include <tuple>
 
 #define DEBUG_TYPE "FindSymbols"
diff --git a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
index 086315feb382..37f6173d30e6 100644
--- a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
+++ b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
@@ -30,6 +30,7 @@
 #include <chrono>
 #include <condition_variable>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <vector>
diff --git a/clang-tools-extra/clangd/GlobalCompilationDatabase.h b/clang-tools-extra/clangd/GlobalCompilationDatabase.h
index 511fa6cb2014..04481fa6ea22 100644
--- a/clang-tools-extra/clangd/GlobalCompilationDatabase.h
+++ b/clang-tools-extra/clangd/GlobalCompilationDatabase.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/StringMap.h"
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/HeaderSourceSwitch.cpp b/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
index 9221fad77d24..ded7a43d4ea1 100644
--- a/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
+++ b/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
@@ -13,6 +13,7 @@
 #include "support/Logger.h"
 #include "support/Path.h"
 #include "clang/AST/Decl.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/HeaderSourceSwitch.h b/clang-tools-extra/clangd/HeaderSourceSwitch.h
index 092b41353aef..1cf9da969e24 100644
--- a/clang-tools-extra/clangd/HeaderSourceSwitch.h
+++ b/clang-tools-extra/clangd/HeaderSourceSwitch.h
@@ -11,6 +11,7 @@
 
 #include "ParsedAST.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Headers.cpp b/clang-tools-extra/clangd/Headers.cpp
index b22589a374cd..fd058e8cfd89 100644
--- a/clang-tools-extra/clangd/Headers.cpp
+++ b/clang-tools-extra/clangd/Headers.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Path.h"
 #include <cstring>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Headers.h b/clang-tools-extra/clangd/Headers.h
index fd739845cdd8..68ccf935fbd4 100644
--- a/clang-tools-extra/clangd/Headers.h
+++ b/clang-tools-extra/clangd/Headers.h
@@ -27,6 +27,7 @@
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem/UniqueID.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Hover.cpp b/clang-tools-extra/clangd/Hover.cpp
index 72c0841d34c6..ca6301999f2c 100644
--- a/clang-tools-extra/clangd/Hover.cpp
+++ b/clang-tools-extra/clangd/Hover.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Support/Format.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Hover.h b/clang-tools-extra/clangd/Hover.h
index 4565e6446db1..a2c4e6094949 100644
--- a/clang-tools-extra/clangd/Hover.h
+++ b/clang-tools-extra/clangd/Hover.h
@@ -13,6 +13,7 @@
 #include "Protocol.h"
 #include "support/Markup.h"
 #include "clang/Index/IndexSymbol.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/IncludeCleaner.cpp b/clang-tools-extra/clangd/IncludeCleaner.cpp
index 3cfa52b40a20..daac976a41e7 100644
--- a/clang-tools-extra/clangd/IncludeCleaner.cpp
+++ b/clang-tools-extra/clangd/IncludeCleaner.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/IncludeCleaner.h b/clang-tools-extra/clangd/IncludeCleaner.h
index 4ce31baaa067..fc3d04da78a8 100644
--- a/clang-tools-extra/clangd/IncludeCleaner.h
+++ b/clang-tools-extra/clangd/IncludeCleaner.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/StringSet.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/IncludeFixer.cpp b/clang-tools-extra/clangd/IncludeFixer.cpp
index d48d5937dc93..5ab993230709 100644
--- a/clang-tools-extra/clangd/IncludeFixer.cpp
+++ b/clang-tools-extra/clangd/IncludeFixer.cpp
@@ -41,6 +41,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
 #include <algorithm>
+#include <optional>
 #include <set>
 #include <string>
 #include <vector>
diff --git a/clang-tools-extra/clangd/IncludeFixer.h b/clang-tools-extra/clangd/IncludeFixer.h
index 50237dd948e4..2a74c23ffa8e 100644
--- a/clang-tools-extra/clangd/IncludeFixer.h
+++ b/clang-tools-extra/clangd/IncludeFixer.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
index 7af39658885b..20a8adcecc73 100644
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -18,6 +18,7 @@
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/ScopeExit.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/JSONTransport.cpp b/clang-tools-extra/clangd/JSONTransport.cpp
index 254e54ad5c23..50b1833a7575 100644
--- a/clang-tools-extra/clangd/JSONTransport.cpp
+++ b/clang-tools-extra/clangd/JSONTransport.cpp
@@ -13,6 +13,7 @@
 #include "support/ThreadCrashReporter.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <system_error>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/ParsedAST.cpp b/clang-tools-extra/clangd/ParsedAST.cpp
index aa84ce35561d..c2846749a708 100644
--- a/clang-tools-extra/clangd/ParsedAST.cpp
+++ b/clang-tools-extra/clangd/ParsedAST.cpp
@@ -50,6 +50,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <vector>
 
 // Force the linker to link in Clang-tidy modules.
diff --git a/clang-tools-extra/clangd/ParsedAST.h b/clang-tools-extra/clangd/ParsedAST.h
index e9133f16473b..8f74c17992d4 100644
--- a/clang-tools-extra/clangd/ParsedAST.h
+++ b/clang-tools-extra/clangd/ParsedAST.h
@@ -34,6 +34,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Protocol.h b/clang-tools-extra/clangd/Protocol.h
index d68efad69175..9cd1955ba95b 100644
--- a/clang-tools-extra/clangd/Protocol.h
+++ b/clang-tools-extra/clangd/Protocol.h
@@ -33,6 +33,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <bitset>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Quality.cpp b/clang-tools-extra/clangd/Quality.cpp
index da8e60ef8d88..72e3154bdbab 100644
--- a/clang-tools-extra/clangd/Quality.cpp
+++ b/clang-tools-extra/clangd/Quality.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cmath>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Quality.h b/clang-tools-extra/clangd/Quality.h
index 88235964a768..2a4efe934f58 100644
--- a/clang-tools-extra/clangd/Quality.h
+++ b/clang-tools-extra/clangd/Quality.h
@@ -33,6 +33,7 @@
 #include "llvm/ADT/StringSet.h"
 #include <algorithm>
 #include <functional>
+#include <optional>
 #include <vector>
 
 namespace llvm {
diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
index 754d31c7155b..56836fd85095 100644
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
+#include <optional>
 #include <set>
 #include <string>
 
diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
index 1f9f851b2817..eaed8870fcbe 100644
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/SemanticSelection.cpp b/clang-tools-extra/clangd/SemanticSelection.cpp
index 3541ede75f5c..fe01c1577bff 100644
--- a/clang-tools-extra/clangd/SemanticSelection.cpp
+++ b/clang-tools-extra/clangd/SemanticSelection.cpp
@@ -25,6 +25,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <queue>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/SourceCode.cpp b/clang-tools-extra/clangd/SourceCode.cpp
index 0ba98f3d838f..90dd37f82f04 100644
--- a/clang-tools-extra/clangd/SourceCode.cpp
+++ b/clang-tools-extra/clangd/SourceCode.cpp
@@ -40,6 +40,7 @@
 #include "llvm/Support/xxhash.h"
 #include <algorithm>
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/SourceCode.h b/clang-tools-extra/clangd/SourceCode.h
index fa4e03b9f2e5..69626c2678d5 100644
--- a/clang-tools-extra/clangd/SourceCode.h
+++ b/clang-tools-extra/clangd/SourceCode.h
@@ -28,6 +28,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
index b65902bd4256..d78d56e367c8 100644
--- a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
+++ b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
@@ -52,6 +52,7 @@
 #include <algorithm>
 #include <iterator>
 #include <map>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/TUScheduler.cpp b/clang-tools-extra/clangd/TUScheduler.cpp
index 44a0d4ac941f..50802d2c8b37 100644
--- a/clang-tools-extra/clangd/TUScheduler.cpp
+++ b/clang-tools-extra/clangd/TUScheduler.cpp
@@ -85,6 +85,7 @@
 #include <functional>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <queue>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/TUScheduler.h b/clang-tools-extra/clangd/TUScheduler.h
index d616814a5edb..f9582a6f3f42 100644
--- a/clang-tools-extra/clangd/TUScheduler.h
+++ b/clang-tools-extra/clangd/TUScheduler.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <chrono>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/XRefs.cpp b/clang-tools-extra/clangd/XRefs.cpp
index 953f911b1398..da33b722876f 100644
--- a/clang-tools-extra/clangd/XRefs.cpp
+++ b/clang-tools-extra/clangd/XRefs.cpp
@@ -61,6 +61,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/XRefs.h b/clang-tools-extra/clangd/XRefs.h
index 60e8e881958d..8af5106078b4 100644
--- a/clang-tools-extra/clangd/XRefs.h
+++ b/clang-tools-extra/clangd/XRefs.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Background.cpp b/clang-tools-extra/clangd/index/Background.cpp
index 2b75b8b58502..f09fb5d29301 100644
--- a/clang-tools-extra/clangd/index/Background.cpp
+++ b/clang-tools-extra/clangd/index/Background.cpp
@@ -49,6 +49,7 @@
 #include <memory>
 #include <mutex>
 #include <numeric>
+#include <optional>
 #include <queue>
 #include <random>
 #include <string>
diff --git a/clang-tools-extra/clangd/index/Background.h b/clang-tools-extra/clangd/index/Background.h
index ac99a151e73b..45f679a16617 100644
--- a/clang-tools-extra/clangd/index/Background.h
+++ b/clang-tools-extra/clangd/index/Background.h
@@ -27,6 +27,7 @@
 #include <condition_variable>
 #include <deque>
 #include <mutex>
+#include <optional>
 #include <queue>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp b/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
index 1de118993a11..c7bbd98a32ce 100644
--- a/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
+++ b/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/BackgroundQueue.cpp b/clang-tools-extra/clangd/index/BackgroundQueue.cpp
index b0dc2acca356..5fb1511353ee 100644
--- a/clang-tools-extra/clangd/index/BackgroundQueue.cpp
+++ b/clang-tools-extra/clangd/index/BackgroundQueue.cpp
@@ -8,6 +8,7 @@
 
 #include "index/Background.h"
 #include "support/Logger.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/FileIndex.cpp b/clang-tools-extra/clangd/index/FileIndex.cpp
index 1080cb0f4b81..95bda42a796c 100644
--- a/clang-tools-extra/clangd/index/FileIndex.cpp
+++ b/clang-tools-extra/clangd/index/FileIndex.cpp
@@ -35,6 +35,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/index/FileIndex.h b/clang-tools-extra/clangd/index/FileIndex.h
index 24ffbc9c7fb5..31757d13eb40 100644
--- a/clang-tools-extra/clangd/index/FileIndex.h
+++ b/clang-tools-extra/clangd/index/FileIndex.h
@@ -31,6 +31,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
index 5406b95eae04..e836d459c2ee 100644
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/JSON.h"
 #include <mutex>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/IndexAction.cpp b/clang-tools-extra/clangd/index/IndexAction.cpp
index a5f8f6b4498c..d97dc40e03a6 100644
--- a/clang-tools-extra/clangd/index/IndexAction.cpp
+++ b/clang-tools-extra/clangd/index/IndexAction.cpp
@@ -22,6 +22,7 @@
 #include <cstddef>
 #include <functional>
 #include <memory>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Serialization.h b/clang-tools-extra/clangd/index/Serialization.h
index 16b80961a981..fceaefed4c0c 100644
--- a/clang-tools-extra/clangd/index/Serialization.h
+++ b/clang-tools-extra/clangd/index/Serialization.h
@@ -29,6 +29,7 @@
 #include "index/Symbol.h"
 #include "clang/Tooling/CompilationDatabase.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/StdLib.cpp b/clang-tools-extra/clangd/index/StdLib.cpp
index ac7388ca30b2..ab9a8ed8cfb3 100644
--- a/clang-tools-extra/clangd/index/StdLib.cpp
+++ b/clang-tools-extra/clangd/index/StdLib.cpp
@@ -8,6 +8,7 @@
 #include "StdLib.h"
 #include <fstream>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/index/StdLib.h b/clang-tools-extra/clangd/index/StdLib.h
index 6df30ace669c..6c170dceba9c 100644
--- a/clang-tools-extra/clangd/index/StdLib.h
+++ b/clang-tools-extra/clangd/index/StdLib.h
@@ -26,6 +26,7 @@
 #include "index/Symbol.h"
 #include "support/ThreadsafeFS.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.cpp b/clang-tools-extra/clangd/index/SymbolCollector.cpp
index 4c865a4317ba..5f9c8bbb4ee9 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ b/clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.h b/clang-tools-extra/clangd/index/SymbolCollector.h
index f3d8d80aa8de..6acce1f3e3c4 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.h
+++ b/clang-tools-extra/clangd/index/SymbolCollector.h
@@ -25,6 +25,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/YAMLSerialization.cpp b/clang-tools-extra/clangd/index/YAMLSerialization.cpp
index 593ce30501b0..c51489fd5dc6 100644
--- a/clang-tools-extra/clangd/index/YAMLSerialization.cpp
+++ b/clang-tools-extra/clangd/index/YAMLSerialization.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdint>
+#include <optional>
 
 namespace {
 struct YIncludeHeaderWithReferences;
diff --git a/clang-tools-extra/clangd/index/dex/Dex.cpp b/clang-tools-extra/clangd/index/dex/Dex.cpp
index c66e7f0d936c..0e94f59187de 100644
--- a/clang-tools-extra/clangd/index/dex/Dex.cpp
+++ b/clang-tools-extra/clangd/index/dex/Dex.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include <algorithm>
+#include <optional>
 #include <queue>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
index 7bbcba339833..763382204dc2 100644
--- a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
+++ b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
@@ -21,6 +21,7 @@
 #include "llvm/LineEditor/LineEditor.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Signals.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/remote/server/Server.cpp b/clang-tools-extra/clangd/index/remote/server/Server.cpp
index 016ae728d040..5d2c82e2c86a 100644
--- a/clang-tools-extra/clangd/index/remote/server/Server.cpp
+++ b/clang-tools-extra/clangd/index/remote/server/Server.cpp
@@ -36,6 +36,7 @@
 #include <grpc++/grpc++.h>
 #include <grpc++/health_check_service_interface.h>
 #include <memory>
+#include <optional>
 #include <string>
 #include <thread>
 #include <utility>
diff --git a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
index 3158863cbb3c..ff17ddd420b7 100644
--- a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
+++ b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
@@ -13,6 +13,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Rename.cpp b/clang-tools-extra/clangd/refactor/Rename.cpp
index 5145ba4811ad..afddab007358 100644
--- a/clang-tools-extra/clangd/refactor/Rename.cpp
+++ b/clang-tools-extra/clangd/refactor/Rename.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/JSON.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Rename.h b/clang-tools-extra/clangd/refactor/Rename.h
index c10aa5a3ad20..6b917d561180 100644
--- a/clang-tools-extra/clangd/refactor/Rename.h
+++ b/clang-tools-extra/clangd/refactor/Rename.h
@@ -13,6 +13,7 @@
 #include "SourceCode.h"
 #include "clang/Basic/LangOptions.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Tweak.h b/clang-tools-extra/clangd/refactor/Tweak.h
index 5e7b77fcba84..f91faf2aedcf 100644
--- a/clang-tools-extra/clangd/refactor/Tweak.h
+++ b/clang-tools-extra/clangd/refactor/Tweak.h
@@ -28,6 +28,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
index 8c2bf9f8eaf2..410dec0b9100 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
@@ -39,6 +39,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstddef>
+#include <optional>
 #include <set>
 #include <string>
 #include <unordered_map>
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
index 87890b9a4b0b..1e09da9aa20b 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include <cstddef>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp b/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
index f2ae97c08069..7a89ce7dc3cf 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp b/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
index 04f4a2c8fdb7..aabaed045c3d 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
@@ -16,6 +16,7 @@
 #include <AST.h>
 #include <climits>
 #include <memory>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp b/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
index c645859175fb..a259deb0a915 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
@@ -72,6 +72,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_os_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp b/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
index 3fb9ac52ee32..dbaf2a5d5c36 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
@@ -23,6 +23,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
index ec02beb7e46f..51d299ee63de 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
@@ -16,6 +16,7 @@
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Tooling/Core/Replacement.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/tool/Check.cpp b/clang-tools-extra/clangd/tool/Check.cpp
index f2677d378ffc..3250571d4bce 100644
--- a/clang-tools-extra/clangd/tool/Check.cpp
+++ b/clang-tools-extra/clangd/tool/Check.cpp
@@ -54,6 +54,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp b/clang-tools-extra/clangd/tool/ClangdMain.cpp
index 3975ae967f90..fa6bda1c6d1e 100644
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -44,6 +44,7 @@
 #include <cstdlib>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <thread>
 #include <utility>
diff --git a/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp b/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
index c3ad1b8cfb66..a9a30eac4368 100644
--- a/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/ClangdTests.cpp b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
index 226fbad649b2..05630629009c 100644
--- a/clang-tools-extra/clangd/unittests/ClangdTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
@@ -40,6 +40,7 @@
 #include <algorithm>
 #include <chrono>
 #include <iostream>
+#include <optional>
 #include <random>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
index 1c87cea32916..8d434a2793e2 100644
--- a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/ConfigTesting.h b/clang-tools-extra/clangd/unittests/ConfigTesting.h
index f31a9c0591a4..c06a06127673 100644
--- a/clang-tools-extra/clangd/unittests/ConfigTesting.h
+++ b/clang-tools-extra/clangd/unittests/ConfigTesting.h
@@ -14,6 +14,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "gmock/gmock.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp b/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
index c52413a12d50..839f4c8e57a5 100644
--- a/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
+++ b/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp b/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
index 2d4cddeb8670..71bcb1234ba8 100644
--- a/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
+++ b/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
@@ -24,6 +24,7 @@
 #include "gtest/gtest.h"
 #include <chrono>
 #include <fstream>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp b/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
index 4a61ada1dc75..f6bc9a6248cf 100644
--- a/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/HeadersTests.cpp b/clang-tools-extra/clangd/unittests/HeadersTests.cpp
index 66caa5ebab95..b14a14f0528b 100644
--- a/clang-tools-extra/clangd/unittests/HeadersTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HeadersTests.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp b/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
index 97a4316928a8..b23c00edc99e 100644
--- a/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
+++ b/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
@@ -10,6 +10,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/LSPClient.cpp b/clang-tools-extra/clangd/unittests/LSPClient.cpp
index aaadc62e68f3..027bf57a8a04 100644
--- a/clang-tools-extra/clangd/unittests/LSPClient.cpp
+++ b/clang-tools-extra/clangd/unittests/LSPClient.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 #include <condition_variable>
+#include <optional>
 #include <queue>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/PreambleTests.cpp b/clang-tools-extra/clangd/unittests/PreambleTests.cpp
index f38e297049a3..eb071e39c41d 100644
--- a/clang-tools-extra/clangd/unittests/PreambleTests.cpp
+++ b/clang-tools-extra/clangd/unittests/PreambleTests.cpp
@@ -25,6 +25,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
index 459b4dbb9361..eb5f60c3b935 100644
--- a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <tuple>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp b/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
index 27854004094e..08523edfc558 100644
--- a/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
@@ -26,6 +26,7 @@
 #include "gtest/gtest.h"
 
 #include <memory>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp b/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
index f68f87fef156..ad76d7dcf554 100644
--- a/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
@@ -11,6 +11,7 @@
 #include "XRefs.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/SyncAPI.cpp b/clang-tools-extra/clangd/unittests/SyncAPI.cpp
index 52f47b01b4e1..2c4fde7d1895 100644
--- a/clang-tools-extra/clangd/unittests/SyncAPI.cpp
+++ b/clang-tools-extra/clangd/unittests/SyncAPI.cpp
@@ -9,6 +9,7 @@
 #include "SyncAPI.h"
 #include "Protocol.h"
 #include "index/Index.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/SyncAPI.h b/clang-tools-extra/clangd/unittests/SyncAPI.h
index 46202239105b..6b4e3fc608e9 100644
--- a/clang-tools-extra/clangd/unittests/SyncAPI.h
+++ b/clang-tools-extra/clangd/unittests/SyncAPI.h
@@ -18,6 +18,7 @@
 #include "ClangdServer.h"
 #include "Protocol.h"
 #include "index/Index.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp b/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
index 67d6fd2cbe56..c7e28a0e213a 100644
--- a/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
@@ -36,6 +36,7 @@
 #include <chrono>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clangd/unittests/TestFS.cpp b/clang-tools-extra/clangd/unittests/TestFS.cpp
index b820bc7d02b3..be26a6ccf25f 100644
--- a/clang-tools-extra/clangd/unittests/TestFS.cpp
+++ b/clang-tools-extra/clangd/unittests/TestFS.cpp
@@ -13,6 +13,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestFS.h b/clang-tools-extra/clangd/unittests/TestFS.h
index 7d3d4d3d03dd..3e4ac3bab1c9 100644
--- a/clang-tools-extra/clangd/unittests/TestFS.h
+++ b/clang-tools-extra/clangd/unittests/TestFS.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestWorkspace.cpp b/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
index bca24fca3a04..662eef63d25a 100644
--- a/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
+++ b/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
@@ -9,6 +9,7 @@
 #include "TestWorkspace.h"
 #include "index/FileIndex.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestWorkspace.h b/clang-tools-extra/clangd/unittests/TestWorkspace.h
index 4467c7efb74a..bc6aee1c58d1 100644
--- a/clang-tools-extra/clangd/unittests/TestWorkspace.h
+++ b/clang-tools-extra/clangd/unittests/TestWorkspace.h
@@ -19,6 +19,7 @@
 #include "TestTU.h"
 #include "index/Index.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/XRefsTests.cpp b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
index 1a25b5d69d7a..ae19656f6f9a 100644
--- a/clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/ScopedPrinter.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp b/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
index 8d2bc4d15d7b..133b83ba93fd 100644
--- a/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
+++ b/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
@@ -13,6 +13,7 @@
 #include "gtest/gtest.h"
 #include <atomic>
 #include <chrono>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp b/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
index 59885cec0570..12836d0926e2 100644
--- a/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
+++ b/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/xpc/XPCTransport.cpp b/clang-tools-extra/clangd/xpc/XPCTransport.cpp
index 9c43647c3c76..dac8e29efae1 100644
--- a/clang-tools-extra/clangd/xpc/XPCTransport.cpp
+++ b/clang-tools-extra/clangd/xpc/XPCTransport.cpp
@@ -11,6 +11,7 @@
 #include "support/Logger.h"
 #include "llvm/Support/Errno.h"
 
+#include <optional>
 #include <xpc/xpc.h>
 
 using namespace llvm;
diff --git a/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h b/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
index e9af9a5bb04f..e8f4240b8fa3 100644
--- a/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
+++ b/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
@@ -30,6 +30,7 @@
 
 #include "clang-pseudo/Token.h"
 #include "clang/Basic/TokenKinds.h"
+#include <optional>
 #include <variant>
 #include <vector>
 
diff --git a/clang-tools-extra/pseudo/lib/DirectiveTree.cpp b/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
index 4835fc24071a..4e866815e63b 100644
--- a/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
+++ b/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/TokenKinds.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 #include <variant>
 
 namespace clang {
diff --git a/clang-tools-extra/pseudo/lib/Forest.cpp b/clang-tools-extra/pseudo/lib/Forest.cpp
index 78e7983d28bc..e6b2d2ec0f90 100644
--- a/clang-tools-extra/pseudo/lib/Forest.cpp
+++ b/clang-tools-extra/pseudo/lib/Forest.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 
 namespace clang {
 namespace pseudo {
diff --git a/clang-tools-extra/pseudo/lib/GLR.cpp b/clang-tools-extra/pseudo/lib/GLR.cpp
index e49cbc40efce..a4169dd96f4a 100644
--- a/clang-tools-extra/pseudo/lib/GLR.cpp
+++ b/clang-tools-extra/pseudo/lib/GLR.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <queue>
 
 #define DEBUG_TYPE "GLR.cpp"
diff --git a/clang-tools-extra/pseudo/tool/ClangPseudo.cpp b/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
index c6d06739e7b0..c22ea171c96c 100644
--- a/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
+++ b/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
+#include <optional>
 
 using clang::pseudo::ForestNode;
 using clang::pseudo::Token;
diff --git a/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp b/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
index 31a444f2e4ec..437d9b4df8fe 100644
--- a/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
@@ -5,6 +5,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Tooling/Tooling.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp b/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
index 5dcec035c476..d861e86284b3 100644
--- a/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
@@ -6,6 +6,7 @@
 #include "llvm/Testing/Support/Annotations.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp b/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
index 5394e7526809..964f5f74a2bf 100644
--- a/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
@@ -5,6 +5,7 @@
 #include "llvm/HeaderGuardCheck.h"
 #include "llvm/IncludeOrderCheck.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang::tidy::llvm_check;
 
diff --git a/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp b/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
index e1ebad73bb73..873259414b74 100644
--- a/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
@@ -15,6 +15,7 @@
 #include "clang/Tooling/Transformer/Transformer.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {