diff --git a/clang/include/clang/Basic/Builtins.h b/clang/include/clang/Basic/Builtins.h
--- a/clang/include/clang/Basic/Builtins.h
+++ b/clang/include/clang/Basic/Builtins.h
@@ -224,7 +224,7 @@
 
   /// Returns true if this is a libc/libm function without the '__builtin_'
   /// prefix.
-  static bool isBuiltinFunc(const char *Name);
+  static bool isBuiltinFunc(llvm::StringRef Name);
 
   /// Returns true if this is a builtin that can be redeclared.  Returns true
   /// for non-builtins.
diff --git a/clang/lib/Basic/Builtins.cpp b/clang/lib/Basic/Builtins.cpp
--- a/clang/lib/Basic/Builtins.cpp
+++ b/clang/lib/Basic/Builtins.cpp
@@ -47,8 +47,7 @@
     AuxTSRecords = AuxTarget->getTargetBuiltins();
 }
 
-bool Builtin::Context::isBuiltinFunc(const char *Name) {
-  StringRef FuncName(Name);
+bool Builtin::Context::isBuiltinFunc(llvm::StringRef FuncName) {
   for (unsigned i = Builtin::NotBuiltin + 1; i != Builtin::FirstTSBuiltin; ++i)
     if (FuncName.equals(BuiltinInfo[i].Name))
       return strchr(BuiltinInfo[i].Attributes, 'f') != nullptr;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1096,7 +1096,7 @@
       if (!S.checkStringLiteralArgumentAttr(AL, I, BuiltinName, &LiteralLoc))
         return;
 
-      if (Builtin::Context::isBuiltinFunc(BuiltinName.data()))
+      if (Builtin::Context::isBuiltinFunc(BuiltinName))
         AddBuiltinName(BuiltinName);
       else
         S.Diag(LiteralLoc, diag::warn_attribute_no_builtin_invalid_builtin_name)