Index: lib/Sema/SemaStmtAsm.cpp
===================================================================
--- lib/Sema/SemaStmtAsm.cpp
+++ lib/Sema/SemaStmtAsm.cpp
@@ -536,7 +536,10 @@
   LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
                                          Location);
 
-  if (!Label->isMSAsmLabel()) {
+  if (Label->isMSAsmLabel()) {
+    // If we have previously created this label implicitly, mark it as used.
+    Label->markUsed(Context);
+  } else {
     // Otherwise, insert it, but only resolve it if we have seen the label itself.
     std::string InternalName;
     llvm::raw_string_ostream OS(InternalName);
Index: test/Sema/ms-inline-asm.c
===================================================================
--- test/Sema/ms-inline-asm.c
+++ test/Sema/ms-inline-asm.c
@@ -1,5 +1,5 @@
 // REQUIRES: x86-registered-target
-// RUN: %clang_cc1 %s -triple x86_64-apple-darwin10 -fasm-blocks -Wno-microsoft -verify -fsyntax-only
+// RUN: %clang_cc1 %s -triple x86_64-apple-darwin10 -fasm-blocks -Wno-microsoft -Wunused-label -verify -fsyntax-only
 
 void t1(void) { 
  __asm __asm // expected-error {{__asm used with no assembly instructions}}
@@ -146,5 +146,11 @@
 
 void t11() {
 foo:
-  __asm mov eax, foo // expected-error {{use of undeclared label 'foo'}}
+  __asm mov eax, foo // expected-error {{use of undeclared label 'foo'}} expected-warning {{unused label 'foo'}}
+}
+
+void t12() {
+  __asm foo:
+  __asm bar: // expected-warning {{unused label 'bar'}}
+  __asm jmp foo
 }