diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index eaa8b58..ff8acde 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -1065,7 +1065,7 @@
     break;
   }
   case Decl::ObjCCompatibleAlias: 
-    ErrorUnsupported(D, "Objective-C compatible alias");
+    // compatibility-alias is a directive and has no code gen.
     break;
 
   case Decl::LinkageSpec: {