Index: llvm/include/llvm/Support/ThreadPool.h
===================================================================
--- llvm/include/llvm/Support/ThreadPool.h
+++ llvm/include/llvm/Support/ThreadPool.h
@@ -35,17 +35,8 @@
 /// for some work to become available.
 class ThreadPool {
 public:
-#ifndef _MSC_VER
-  using VoidTy = void;
   using TaskTy = std::function<void()>;
   using PackagedTaskTy = std::packaged_task<void()>;
-#else
-  // MSVC 2013 has a bug and can't use std::packaged_task<void()>;
-  // We force it to use bool(bool) instead.
-  using VoidTy = bool;
-  using TaskTy = std::function<bool(bool)>;
-  using PackagedTaskTy = std::packaged_task<bool(bool)>;
-#endif
 
   /// Construct a pool with the number of core available on the system (or
   /// whatever the value returned by std::thread::hardware_concurrency() is).
@@ -60,30 +51,17 @@
   /// Asynchronous submission of a task to the pool. The returned future can be
   /// used to wait for the task to finish and is *non-blocking* on destruction.
   template <typename Function, typename... Args>
-  inline std::shared_future<VoidTy> async(Function &&F, Args &&... ArgList) {
+  inline std::shared_future<void> async(Function &&F, Args &&... ArgList) {
     auto Task =
         std::bind(std::forward<Function>(F), std::forward<Args>(ArgList)...);
-#ifndef _MSC_VER
     return asyncImpl(std::move(Task));
-#else
-    // This lambda has to be marked mutable because MSVC 2013's std::bind call
-    // operator isn't const qualified.
-    return asyncImpl([Task](VoidTy) mutable -> VoidTy {
-      Task();
-      return VoidTy();
-    });
-#endif
   }
 
   /// Asynchronous submission of a task to the pool. The returned future can be
   /// used to wait for the task to finish and is *non-blocking* on destruction.
   template <typename Function>
-  inline std::shared_future<VoidTy> async(Function &&F) {
-#ifndef _MSC_VER
+  inline std::shared_future<void> async(Function &&F) {
     return asyncImpl(std::forward<Function>(F));
-#else
-    return asyncImpl([F] (VoidTy) -> VoidTy { F(); return VoidTy(); });
-#endif
   }
 
   /// Blocking wait for all the threads to complete and the queue to be empty.
@@ -93,7 +71,7 @@
 private:
   /// Asynchronous submission of a task to the pool. The returned future can be
   /// used to wait for the task to finish and is *non-blocking* on destruction.
-  std::shared_future<VoidTy> asyncImpl(TaskTy F);
+  std::shared_future<void> asyncImpl(TaskTy F);
 
   /// Threads in flight
   std::vector<llvm::thread> Threads;
Index: llvm/lib/Support/ThreadPool.cpp
===================================================================
--- llvm/lib/Support/ThreadPool.cpp
+++ llvm/lib/Support/ThreadPool.cpp
@@ -53,11 +53,7 @@
           Tasks.pop();
         }
         // Run the task we just grabbed
-#ifndef _MSC_VER
         Task();
-#else
-        Task(/* unused */ false);
-#endif
 
         {
           // Adjust `ActiveThreads`, in case someone waits on ThreadPool::wait()
@@ -82,7 +78,7 @@
                            [&] { return !ActiveThreads && Tasks.empty(); });
 }
 
-std::shared_future<ThreadPool::VoidTy> ThreadPool::asyncImpl(TaskTy Task) {
+std::shared_future<void> ThreadPool::asyncImpl(TaskTy Task) {
   /// Wrap the Task in a packaged_task to return a future object.
   PackagedTaskTy PackagedTask(std::move(Task));
   auto Future = PackagedTask.get_future();
@@ -128,25 +124,16 @@
   while (!Tasks.empty()) {
     auto Task = std::move(Tasks.front());
     Tasks.pop();
-#ifndef _MSC_VER
-        Task();
-#else
-        Task(/* unused */ false);
-#endif
+    Task();
   }
 }
 
-std::shared_future<ThreadPool::VoidTy> ThreadPool::asyncImpl(TaskTy Task) {
-#ifndef _MSC_VER
+std::shared_future<void> ThreadPool::asyncImpl(TaskTy Task) {
   // Get a Future with launch::deferred execution using std::async
   auto Future = std::async(std::launch::deferred, std::move(Task)).share();
   // Wrap the future so that both ThreadPool::wait() can operate and the
   // returned future can be sync'ed on.
   PackagedTaskTy PackagedTask([Future]() { Future.get(); });
-#else
-  auto Future = std::async(std::launch::deferred, std::move(Task), false).share();
-  PackagedTaskTy PackagedTask([Future](bool) -> bool { Future.get(); return false; });
-#endif
   Tasks.push(std::move(PackagedTask));
   return Future;
 }