diff --git a/contrib/llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp b/contrib/llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp
index c05e5f02070..4e7541fa671 100644
--- a/contrib/llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/contrib/llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp
@@ -12997,7 +12997,8 @@ bool Sema::CheckLiteralOperatorDeclaration(FunctionDecl *FnDecl) {
 
   StringRef LiteralName
     = FnDecl->getDeclName().getCXXLiteralIdentifier()->getName();
-  if (LiteralName[0] != '_') {
+  if (LiteralName[0] != '_' &&
+      !getSourceManager().isInSystemHeader(FnDecl->getLocation())) {
     // C++11 [usrlit.suffix]p1:
     //   Literal suffix identifiers that do not start with an underscore
     //   are reserved for future standardization.