3 files changed, 9 insertions, 0 deletions
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index c10df6fc634..f26ed159d1e 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2785,6 +2785,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Args.MakeArgString(A->getValue(Args)));
   }
 
+  if (Args.hasArg(options::OPT_fretain_comments_from_system_headers))
+    CmdArgs.push_back("-fretain-comments-from-system-headers");
+
   // Forward -Xclang arguments to -cc1, and -mllvm arguments to the LLVM option
   // parser.
   Args.AddAllArgValues(CmdArgs, options::OPT_Xclang);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 6d6dbfcc286..6d34425e130 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2151,6 +2151,9 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.EmitMicrosoftInlineAsm = Args.hasArg(OPT_fenable_experimental_ms_inline_asm);
 
+  Opts.RetainCommentsFromSystemHeaders =
+      Args.hasArg(OPT_fretain_comments_from_system_headers);
+
   unsigned SSP = Args.getLastArgIntValue(OPT_stack_protector, 0, Diags);
   switch (SSP) {
   default:
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index fd57bbc237d..bd7c8515f64 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -1026,6 +1026,9 @@ LambdaScopeInfo *Sema::getCurLambda() {
 }
 
 void Sema::ActOnComment(SourceRange Comment) {
+  if (!LangOpts.RetainCommentsFromSystemHeaders &&
+      SourceMgr.isInSystemHeader(Comment.getBegin()))
+    return;
   RawComment RC(SourceMgr, Comment);
   if (RC.isAlmostTrailingComment()) {
     SourceRange MagicMarkerRange(Comment.getBegin(),