diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 196ab5d..576209f 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2421,7 +2421,7 @@
     break;
   }
   case Decl::ObjCCompatibleAlias:
-    // compatibility-alias is a directive and has no code gen.
+    ObjCRuntime->RegisterAlias(cast<ObjCCompatibleAliasDecl>(D));
     break;
 
   case Decl::LinkageSpec: