diff --git a/llvm/utils/gn/secondary/clang/lib/ExtractAPI/BUILD.gn b/llvm/utils/gn/secondary/clang/lib/ExtractAPI/BUILD.gn
index 1e189cae13c85d..a17fe06ad509b7 100644
--- a/llvm/utils/gn/secondary/clang/lib/ExtractAPI/BUILD.gn
+++ b/llvm/utils/gn/secondary/clang/lib/ExtractAPI/BUILD.gn
@@ -10,6 +10,7 @@ static_library("ExtractAPI") {
   ]
   sources = [
     "API.cpp",
+    "AvailabilityInfo.cpp",
     "DeclarationFragments.cpp",
     "ExtractAPIConsumer.cpp",
     "Serialization/SerializerBase.cpp",