diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index e9116bc..84d992c 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2769,7 +2769,10 @@
                                 ObjCMethodDecl *oldMethod) {
 
   // Merge the attributes, including deprecated/unavailable
-  mergeDeclAttributes(newMethod, oldMethod, AMK_Override);
+  AvailabilityMergeKind MergeKind =
+    isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
+                                                   : AMK_Override;
+  mergeDeclAttributes(newMethod, oldMethod, MergeKind);
 
   // Merge attributes from the parameters.
   ObjCMethodDecl::param_const_iterator oi = oldMethod->param_begin(),