diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index b328b2f..5f0b48b 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -45,6 +45,7 @@
     if (CheckBuiltinCFStringArgument(TheCall->getArg(0)))
       return true;
     return TheCall.take();
+  case Builtin::BI__builtin_stdarg_start:
   case Builtin::BI__builtin_va_start:
     if (SemaBuiltinVAStart(TheCall.get()))
       return true;