Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp	(revision 164362)
+++ lib/CodeGen/CGBuiltin.cpp	(working copy)
@@ -1314,7 +1314,11 @@
     llvm::StringRef Str = cast<StringLiteral>(AnnotationStrExpr)->getString();
     return RValue::get(EmitAnnotationCall(F, AnnVal, Str, E->getExprLoc()));
   }
+  case Builtin::BI__noop: {
+    Value *F = CGM.getIntrinsic(Intrinsic::donothing);
+    return RValue::get(Builder.CreateCall(F));
   }
+  }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit
   // the call using the normal call path, but using the unmangled