diff --git a/llvm/utils/gn/secondary/lldb/source/Host/BUILD.gn b/llvm/utils/gn/secondary/lldb/source/Host/BUILD.gn
index 39c3efaa040a..7c9edfb016d7 100644
--- a/llvm/utils/gn/secondary/lldb/source/Host/BUILD.gn
+++ b/llvm/utils/gn/secondary/lldb/source/Host/BUILD.gn
@@ -16,6 +16,7 @@ static_library("Host") {
   ]
   public_deps = [ "//llvm/utils/gn/build/libs/xml" ]
   sources = [
+    "common/Alarm.cpp",
     "common/File.cpp",
     "common/FileAction.cpp",
     "common/FileCache.cpp",