diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index cb5998437b0a..ac4a5bdcd500 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -155,6 +155,8 @@ public:
   object_t *createCOFFEntity(StringRef Name, list_t &List);
 
   void defineSection(MCSectionCOFF const &Sec);
+
+  COFFSymbol *getLinkedSymbol(const MCSymbol &Symbol);
   void DefineSymbol(const MCSymbol &Symbol, MCAssembler &Assembler,
                     const MCAsmLayout &Layout);
 
@@ -353,6 +355,21 @@ static uint64_t getSymbolValue(const MCSymbol &Symbol,
   return Res;
 }
 
+COFFSymbol *WinCOFFObjectWriter::getLinkedSymbol(const MCSymbol &Symbol) {
+  if (!Symbol.isVariable())
+    return nullptr;
+
+  const MCSymbolRefExpr *SymRef =
+      dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
+  if (!SymRef)
+    return nullptr;
+
+  const MCSymbol &Aliasee = SymRef->getSymbol();
+  if (!Aliasee.isUndefined())
+    return nullptr;
+  return GetOrCreateCOFFSymbol(&Aliasee);
+}
+
 /// This function takes a symbol data object from the assembler
 /// and creates the associated COFF symbol staging object.
 void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &Symbol,
@@ -367,32 +384,23 @@ void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &Symbol,
       report_fatal_error("conflicting sections for symbol");
   }
 
+  COFFSymbol *Local = nullptr;
   if (cast<MCSymbolCOFF>(Symbol).isWeakExternal()) {
     coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
 
-    if (Symbol.isVariable()) {
-      const MCSymbolRefExpr *SymRef =
-          dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
-
-      if (!SymRef)
-        report_fatal_error("Weak externals may only alias symbols");
-
-      coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
-    } else {
+    COFFSymbol *WeakDefault = getLinkedSymbol(Symbol);
+    if (!WeakDefault) {
       std::string WeakName = (".weak." + Symbol.getName() + ".default").str();
-      COFFSymbol *WeakDefault = createSymbol(WeakName);
-
+      WeakDefault = createSymbol(WeakName);
       if (!Sec)
         WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
       else
         WeakDefault->Section = Sec;
-
-      WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
-      WeakDefault->Data.Type = 0;
-      WeakDefault->Data.Value = getSymbolValue(Symbol, Layout);
-      coff_symbol->Other = WeakDefault;
+      Local = WeakDefault;
     }
 
+    coff_symbol->Other = WeakDefault;
+
     // Setup the Weak External auxiliary symbol.
     coff_symbol->Aux.resize(1);
     memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
@@ -400,32 +408,32 @@ void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &Symbol,
     coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
     coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
         COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
-
-    coff_symbol->MC = &Symbol;
   } else {
-    coff_symbol->Data.Value = getSymbolValue(Symbol, Layout);
-
-    const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(Symbol);
-    coff_symbol->Data.Type = SymbolCOFF.getType();
-    coff_symbol->Data.StorageClass = SymbolCOFF.getClass();
-
-    // If no storage class was specified in the streamer, define it here.
-    if (coff_symbol->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
-      bool IsExternal = Symbol.isExternal() ||
-                        (!Symbol.getFragment() && !Symbol.isVariable());
-
-      coff_symbol->Data.StorageClass = IsExternal
-                                           ? COFF::IMAGE_SYM_CLASS_EXTERNAL
-                                           : COFF::IMAGE_SYM_CLASS_STATIC;
-    }
-
     if (!Base)
       coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
     else
       coff_symbol->Section = Sec;
-
-    coff_symbol->MC = &Symbol;
+    Local = coff_symbol;
   }
+
+  if (Local) {
+    Local->Data.Value = getSymbolValue(Symbol, Layout);
+
+    const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(Symbol);
+    Local->Data.Type = SymbolCOFF.getType();
+    Local->Data.StorageClass = SymbolCOFF.getClass();
+
+    // If no storage class was specified in the streamer, define it here.
+    if (Local->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
+      bool IsExternal = Symbol.isExternal() ||
+                        (!Symbol.getFragment() && !Symbol.isVariable());
+
+      Local->Data.StorageClass = IsExternal ? COFF::IMAGE_SYM_CLASS_EXTERNAL
+                                            : COFF::IMAGE_SYM_CLASS_STATIC;
+    }
+  }
+
+  coff_symbol->MC = &Symbol;
 }
 
 // Maximum offsets for different string table entry encodings.
diff --git a/llvm/test/MC/COFF/weak-alias-local.s b/llvm/test/MC/COFF/weak-alias-local.s
new file mode 100644
index 000000000000..01f2ac390a59
--- /dev/null
+++ b/llvm/test/MC/COFF/weak-alias-local.s
@@ -0,0 +1,43 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-win32 %s -o %t.o
+// RUN: llvm-readobj -t %t.o | FileCheck %s
+
+// test that we create an external symbol for a to point to.
+
+        .data
+        .long 123
+b:
+        .long   42
+        .weak   a
+a=b
+
+// CHECK:      Symbol {
+// CHECK:        Name: b
+// CHECK-NEXT:   Value: 4
+// CHECK-NEXT:   Section: .data (2)
+// CHECK-NEXT:   BaseType: Null (0x0)
+// CHECK-NEXT:   ComplexType: Null (0x0)
+// CHECK-NEXT:   StorageClass: Static (0x3)
+// CHECK-NEXT:   AuxSymbolCount: 0
+// CHECK-NEXT: }
+// CHECK-NEXT: Symbol {
+// CHECK-NEXT:   Name: a
+// CHECK-NEXT:   Value: 0
+// CHECK-NEXT:   Section: IMAGE_SYM_UNDEFINED (0)
+// CHECK-NEXT:   BaseType: Null (0x0)
+// CHECK-NEXT:   ComplexType: Null (0x0)
+// CHECK-NEXT:   StorageClass: WeakExternal (0x69)
+// CHECK-NEXT:   AuxSymbolCount: 1
+// CHECK-NEXT:   AuxWeakExternal {
+// CHECK-NEXT:     Linked: .weak.a.default (9)
+// CHECK-NEXT:     Search: Library (0x2)
+// CHECK-NEXT:   }
+// CHECK-NEXT: }
+// CHECK-NEXT: Symbol {
+// CHECK-NEXT:   Name: .weak.a.default
+// CHECK-NEXT:   Value: 4
+// CHECK-NEXT:   Section: .data (2)
+// CHECK-NEXT:   BaseType: Null (0x0)
+// CHECK-NEXT:   ComplexType: Null (0x0)
+// CHECK-NEXT:   StorageClass: External (0x2)
+// CHECK-NEXT:   AuxSymbolCount: 0
+// CHECK-NEXT: }
diff --git a/llvm/test/MC/COFF/weak.s b/llvm/test/MC/COFF/weak.s
index 6086749d80de..e0d077840f15 100644
--- a/llvm/test/MC/COFF/weak.s
+++ b/llvm/test/MC/COFF/weak.s
@@ -34,6 +34,16 @@ LBB0_2:                                 # %return
 
 // CHECK: Symbols [
 
+// CHECK:      Symbol {
+// CHECK:        Name: _main
+// CHECK-NEXT:   Value: 0
+// CHECK-NEXT:   Section: .text
+// CHECK-NEXT:   BaseType: Null
+// CHECK-NEXT:   ComplexType: Function
+// CHECK-NEXT:   StorageClass: External
+// CHECK-NEXT:   AuxSymbolCount: 0
+// CHECK-NEXT: }
+
 // CHECK:      Symbol {
 // CHECK:        Name:           _test_weak
 // CHECK-NEXT:   Value:          0
@@ -67,7 +77,17 @@ LBB0_2:                                 # %return
 // CHECK-NEXT:   StorageClass:   WeakExternal
 // CHECK-NEXT:   AuxSymbolCount: 1
 // CHECK-NEXT:   AuxWeakExternal {
-// CHECK-NEXT:     Linked: _main
+// CHECK-NEXT:     Linked: .weak._test_weak_alias.default
 // CHECK-NEXT:      Search: Library
 // CHECK-NEXT:   }
 // CHECK-NEXT: }
+
+// CHECK:      Symbol {
+// CHECK:        Name: .weak._test_weak_alias.default
+// CHECK-NEXT:   Value: 0
+// CHECK-NEXT:   Section: .text
+// CHECK-NEXT:   BaseType: Null
+// CHECK-NEXT:   ComplexType: Null
+// CHECK-NEXT:   StorageClass: External
+// CHECK-NEXT:   AuxSymbolCount: 0
+// CHECK-NEXT: }