Index: lib/AST/MicrosoftMangle.cpp
===================================================================
--- lib/AST/MicrosoftMangle.cpp
+++ lib/AST/MicrosoftMangle.cpp
@@ -966,16 +966,14 @@
     }

     if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
-      DiagnosticsEngine &Diags = Context.getDiags();
-      unsigned DiagID =
-          Diags.getCustomDiagID(DiagnosticsEngine::Error,
-                                "cannot mangle a local inside this block yet");
-      Diags.Report(BD->getLocation(), DiagID);
-
-      // FIXME: This is completely, utterly, wrong; see ItaniumMangle
-      // for how this should be done.
-      Out << "__block_invoke" << Context.getBlockId(BD, false);
-      Out << '@';
+      auto Discriminator = Context.getBlockId(BD, false);
+      Out << "?_block_invoke";
+      if (Discriminator)
+        Out << '_' << Discriminator;
+      Out << "@@YAXPAU__block_literal";
+      if (Discriminator)
+        Out << '_' << Discriminator;
+      Out << "@@@Z";
     } else if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {
       mangleObjCMethodName(Method);
     } else if (isa<NamedDecl>(DC)) {
Index: test/CodeGenCXX/msabi-blocks.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/msabi-blocks.cpp
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -std=c++11 -fblocks -S -emit-llvm -o - %s | FileCheck %s
+
+auto b = ^() {
+  static int i = 0;
+  return ++i;
+};
+
+
+void f() {
+  auto l = ^() {
+    static int i = 0;
+    return ++i;
+  };
+  auto m = ^() {
+    static int i = 0;
+    return ++i;
+  };
+  auto n = ^() {
+    auto o = ^() {
+      static int i = 0;
+      return ++i;
+    };
+  };
+}
+
+template <typename T>
+void g() {
+  auto p = ^() {
+    static int i = 0;
+    return ++i;
+  };
+}
+
+template void g<char>();
+template void g<int>();
+
+// CHECK: @"\01?i@?1??_block_invoke@@YAXPAU__block_literal@@@Z@4HA" = internal
+// CHECK: @"\01?i@?1??_block_invoke_1@@YAXPAU__block_literal_1@@@Z?1??f@@YAXXZ@4HA" = internal
+// CHECK: @"\01?i@?1??_block_invoke_2@@YAXPAU__block_literal_2@@@Z?1??f@@YAXXZ@4HA" = internal
+// CHECK: @"\01?i@?1??_block_invoke_3@@YAXPAU__block_literal_3@@@Z?1??_block_invoke_4@@YAXPAU__block_literal_4@@@Z?1??f@@YAXXZ@4HA" = internal
+// CHECK: @"\01?i@?2??_block_invoke_5@@YAXPAU__block_literal_5@@@Z?2???$g@D@@YAXXZ@4HA" = linkonce_odr
+// CHECK: @"\01?i@?2??_block_invoke_6@@YAXPAU__block_literal_6@@@Z?2???$g@H@@YAXXZ@4HA" = linkonce_odr