diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 49e37faae779d26b8581cb41cfd29fa52d01c08b..944eca64ba6ecd743c95d60243c04177d4eff204 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -484,7 +484,6 @@ def err_no_nsconstant_string_class : Error<
   "cannot find interface declaration for %0">;
 def err_recursive_superclass : Error<
   "trying to recursively use %0 as superclass of %1">;
-def warn_previous_alias_decl : Warning<"previously declared alias is ignored">;
 def err_conflicting_aliasing_type : Error<"conflicting types for alias %0">;
 def warn_undef_interface : Warning<"cannot find interface declaration for %0">;
 def warn_duplicate_protocol_def : Warning<"duplicate protocol definition of %0 is ignored">;
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 618c9d99e1bcf8747c7e72c5de3410893e515bef..e52f7435a32b9daaf4d8c3a823fd6bd480a30a30 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -603,10 +603,7 @@ Decl *Sema::ActOnCompatibilityAlias(SourceLocation AtLoc,
   NamedDecl *ADecl = LookupSingleName(TUScope, AliasName, AliasLocation,
                                       LookupOrdinaryName, ForRedeclaration);
   if (ADecl) {
-    if (isa<ObjCCompatibleAliasDecl>(ADecl))
-      Diag(AliasLocation, diag::warn_previous_alias_decl);
-    else
-      Diag(AliasLocation, diag::err_conflicting_aliasing_type) << AliasName;
+    Diag(AliasLocation, diag::err_conflicting_aliasing_type) << AliasName;
     Diag(ADecl->getLocation(), diag::note_previous_declaration);
     return 0;
   }
diff --git a/test/Misc/warning-flags.c b/test/Misc/warning-flags.c
index 3293e02a440c3dd1461ff25751e5ab9aa3917a65..57da3f9c9e06c09fdeba509b74eec91de63e42a2 100644
--- a/test/Misc/warning-flags.c
+++ b/test/Misc/warning-flags.c
@@ -18,7 +18,7 @@ This test serves two purposes:
 
 The list of warnings below should NEVER grow.  It should gradually shrink to 0.
 
-CHECK: Warnings without flags (141):
+CHECK: Warnings without flags (140):
 CHECK-NEXT:   ext_delete_void_ptr_operand
 CHECK-NEXT:   ext_enum_friend
 CHECK-NEXT:   ext_expected_semi_decl_list
@@ -136,7 +136,6 @@ CHECK-NEXT:   warn_pragma_unused_expected_punc
 CHECK-NEXT:   warn_pragma_unused_expected_var
 CHECK-NEXT:   warn_pragma_unused_expected_var_arg
 CHECK-NEXT:   warn_pragma_unused_undeclared_var
-CHECK-NEXT:   warn_previous_alias_decl
 CHECK-NEXT:   warn_property_attr_mismatch
 CHECK-NEXT:   warn_property_attribute
 CHECK-NEXT:   warn_property_getter_owning_mismatch