Index: lib/CodeGen/CGBlocks.cpp
===================================================================
--- lib/CodeGen/CGBlocks.cpp
+++ lib/CodeGen/CGBlocks.cpp
@@ -2586,11 +2586,11 @@
     }
   }
 
-  if (!CGM.getLangOpts().BlocksRuntimeOptional)
-    return;
-
-  if (GV->isDeclaration() && GV->hasExternalLinkage())
+  if (CGM.getLangOpts().BlocksRuntimeOptional && GV->isDeclaration() &&
+      GV->hasExternalLinkage())
     GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
+
+  CGM.setDSOLocal(GV);
 }
 
 llvm::Constant *CodeGenModule::getBlockObjectDispose() {
Index: test/CodeGen/blocks-windows.c
===================================================================
--- test/CodeGen/blocks-windows.c
+++ test/CodeGen/blocks-windows.c
@@ -67,7 +67,7 @@
   return _Block_copy(^{ ++i; return i; });
 }
 
-// CHECK-BLOCKS-IN-BLOCKS-DECL: @_NSConcreteStackBlock = external dllexport global i8*
+// CHECK-BLOCKS-IN-BLOCKS-DECL: @_NSConcreteStackBlock = external dso_local dllexport global i8*
 // CHECK-BLOCKS-IN-BLOCKS-DEFN: @_NSConcreteStackBlock = common dso_local dllexport global [5 x i32]
 // CHECK-BLOCKS-NOT-IN-BLOCKS: @_NSConcreteStackBlock = external dllimport global i8*
 // CHECK-BLOCKS-NOT-IN-BLOCKS-EXTERN: @_NSConcreteStackBlock = external dllimport global i8*