Index: lib/AST/MicrosoftMangle.cpp
===================================================================
--- lib/AST/MicrosoftMangle.cpp
+++ lib/AST/MicrosoftMangle.cpp
@@ -966,16 +966,23 @@
     }
 
     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);
+      DC = getEffectiveDeclContext(BD);
+      unsigned Discriminator = Context.getBlockId(BD, /*Local=*/false);
+      Out << "?_block_invoke";
+      if (Discriminator)
+        Out<< '_' << Discriminator;
       Out << '@';
+      if (const auto *RD = dyn_cast<RecordDecl>(DC))
+        mangleName(RD);
+      else
+        Out << '@';
+      Out << "YAXPAU__block_literal";
+      if (Discriminator)
+        Out<< '_' << Discriminator;
+      Out << "@@@Z";
+      if (isa<RecordDecl>(DC))
+        break;
+      continue;
     } 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 +1,68 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -std=c++11 -fblocks -S -o - -emit-llvm %s | FileCheck %s
+
+void (^b)() = ^{
+  static int i = 0;
+};
+
+// CHECK-DAG: @"\01?i@?1??_block_invoke@@YAXPAU__block_literal@@@Z@4HA" ={{.*}} global i32 0
+
+extern int e(void);
+
+void f(void) {
+  static int i = 0;
+  ^{ static int i = e(); }();
+
+// CHECK-DAG: @"\01?i@?1??_block_invoke_1@@YAXPAU__block_literal_1@@@Z?1??f@@YAXXZ@4HA" ={{.*}} global i32 0
+
+  ^{ static int i = e(); }();
+
+// CHECK-DAG: @"\01?i@?1??_block_invoke_2@@YAXPAU__block_literal_2@@@Z?1??f@@YAXXZ@4HA" ={{.*}} global i32 0
+
+  ^{ ^{ static int i = e(); }(); }();
+
+// CHECK-DAG: @"\01?i@?1??_block_invoke_3@@YAXPAU__block_literal_3@@@Z?1??_block_invoke_4@@YAXPAU__block_literal_4@@@Z?1??f@@YAXXZ@4HA" ={{.*}} global i32 0
+}
+
+
+template <typename>
+void g(void) {
+  ^{ static int i = e(); }();
+}
+
+template void g<char>(void);
+
+// CHECK-DAG: @"\01?i@?2??_block_invoke_5@@YAXPAU__block_literal_5@@@Z?2???$g@D@@YAXXZ@4HA" ={{.*}} global i32 0
+
+template void g<int>(void);
+
+// CHECK-DAG: @"\01?i@?2??_block_invoke_6@@YAXPAU__block_literal_6@@@Z?2???$g@H@@YAXXZ@4HA" ={{.*}} global i32 0
+
+inline void h(void) {
+  ^{ static int i = e(); }();
+}
+
+// CHECK-DAG: @"\01?i@?2??_block_invoke_9@@YAXPAU__block_literal_9@@@Z?2??h@@YAXXZ@4HA" ={{.*}} global i32 0
+
+struct s {
+  int i = ^{ static int i = e(); return ++i; }();
+
+// CHECK-DAG: @"\01?i@?0??_block_invoke_10@s@@YAXPAU__block_literal_10@@@Z@4HA" ={{.*}} global i32 0
+
+  int j = ^{ static int i = e(); return ++i; }();
+
+// CHECK-DAG: @"\01?i@?0??_block_invoke_11@s@@YAXPAU__block_literal_11@@@Z@4HA" ={{.*}} global i32 0
+
+  void m(int i = ^{ static int i = e(); return ++i; }(),
+         int j = ^{ static int i = e(); return ++i; }()) {}
+
+// CHECK-DAG: @"\01?i@?0??_block_invoke_7@@YAXPAU__block_literal_7@@@Z?0??m@s@@QEAAXHH@Z@4HA" ={{.*}} global i32 0
+// CHECK-DAG: @"\01?i@?0??_block_invoke_8@@YAXPAU__block_literal_8@@@Z?0??m@s@@QEAAXHH@Z@4HA" ={{.*}} global i32 0
+};
+
+
+void j(void) {
+  h();
+  struct s s;
+  s.m();
+}
+