diff --git a/include/clang/Basic/DiagnosticSemaKinds.def b/include/clang/Basic/DiagnosticSemaKinds.def
index 05c4656..cce97aa 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.def
+++ b/include/clang/Basic/DiagnosticSemaKinds.def
@@ -361,6 +361,8 @@
      "%0 attribute ignored")
 DIAG(warn_attribute_weak_on_field, WARNING,
      "__weak attribute cannot be specified on a field declaration")
+DIAG(warn_attribute_weak_on_local, WARNING,
+     "__weak attribute cannot be specified on an automatic variable")
 DIAG(warn_attribute_wrong_decl_type, WARNING,
      "'%0' attribute only applies to %select{function|union|"
      "variable and function|function or method}1 types")
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 51c4790..3130f02 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1592,6 +1592,11 @@
     Diag(D.getIdentifierLoc(), diag::err_as_qualified_auto_decl);
     InvalidDecl = true;
   }
+
+  if (NewVD->hasLocalStorage() && NewVD->getType().isObjCGCWeak()) {
+    Diag(D.getIdentifierLoc(), diag::warn_attribute_weak_on_local);
+  }
+
   // Merge the decl with the existing one if appropriate. If the decl is
   // in an outer scope, it isn't the same thing.
   if (PrevDecl && isDeclInScope(PrevDecl, DC, S)) {
diff --git a/test/SemaObjC/objc2-warn-weak-decl.m b/test/SemaObjC/objc2-warn-weak-decl.m
new file mode 100644
index 0000000..8fde620
--- /dev/null
+++ b/test/SemaObjC/objc2-warn-weak-decl.m
@@ -0,0 +1,10 @@
+// RUN: clang -fsyntax-only -fobjc-gc -verify %s
+struct S {
+	__weak id  p;  // expected-warning {{__weak attribute cannot be specified on a field declaration}}
+};
+
+int main ()
+{
+  __weak id  local;  // expected-warning {{__weak attribute cannot be specified on an automatic variable}}
+}
+