Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -4272,6 +4272,8 @@
 def err_nested_redefinition : Error<"nested redefinition of %0">;
 def err_use_with_wrong_tag : Error<
   "use of %0 with tag type that does not match previous declaration">;
+def warn_different_asm_label : Warning<"conflicting asm label">,
+    InGroup<MismatchedTags>;
 def warn_struct_class_tag_mismatch : Warning<
     "%select{struct|interface|class}0%select{| template}1 %2 was previously "
     "declared as a %select{struct|interface|class}3%select{| template}1">,
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -2385,7 +2385,10 @@
     if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
       if (OldA->getLabel() != NewA->getLabel()) {
         // This redeclaration changes __asm__ label.
-        Diag(New->getLocation(), diag::err_different_asm_label);
+        if (New->isUsed())
+          Diag(New->getLocation(), diag::err_different_asm_label);
+        else
+          Diag(New->getLocation(), diag::warn_different_asm_label);
         Diag(OldA->getLocation(), diag::note_previous_declaration);
       }
     } else if (Old->isUsed()) {
Index: test/Sema/asm-label.c
===================================================================
--- test/Sema/asm-label.c
+++ test/Sema/asm-label.c
@@ -10,7 +10,7 @@
 void g() __asm__("gold");  // expected-error{{cannot apply asm label to function after its first use}}
 
 void h() __asm__("hose");  // expected-note{{previous declaration is here}}
-void h() __asm__("hair");  // expected-error{{conflicting asm label}}
+void h() __asm__("hair");  // expected-warning{{conflicting asm label}}
 
 int x;
 int x __asm__("xenon");
@@ -21,7 +21,7 @@
 int y __asm__("yacht");  // expected-error{{cannot apply asm label to variable after its first use}}
 
 int z __asm__("zebra");  // expected-note{{previous declaration is here}}
-int z __asm__("zooms");  // expected-error{{conflicting asm label}}
+int z __asm__("zooms");  // expected-warning{{conflicting asm label}}
 
 
 // No diagnostics on the following.