Index: lld/COFF/ICF.cpp
===================================================================
--- lld/COFF/ICF.cpp
+++ lld/COFF/ICF.cpp
@@ -21,9 +21,9 @@
 #include "Chunks.h"
 #include "Error.h"
 #include "Symbols.h"
-#include "lld/Core/Parallel.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Parallel.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <atomic>
Index: lld/COFF/MapFile.cpp
===================================================================
--- lld/COFF/MapFile.cpp
+++ lld/COFF/MapFile.cpp
@@ -25,7 +25,7 @@
 #include "Symbols.h"
 #include "Writer.h"
 
-#include "lld/Core/Parallel.h"
+#include "llvm/Support/Parallel.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -76,7 +76,7 @@
 static DenseMap<DefinedRegular *, std::string>
 getSymbolStrings(ArrayRef<DefinedRegular *> Syms) {
   std::vector<std::string> Str(Syms.size());
-  for_each_n(parallel::par, (size_t)0, Syms.size(), [&](size_t I) {
+  for_each_n(llvm::parallel::par, (size_t)0, Syms.size(), [&](size_t I) {
     raw_string_ostream OS(Str[I]);
     writeHeader(OS, Syms[I]->getRVA(), 0, 0);
     OS << indent(2) << toString(*Syms[I]);
Index: lld/COFF/Writer.cpp
===================================================================
--- lld/COFF/Writer.cpp
+++ lld/COFF/Writer.cpp
@@ -17,13 +17,13 @@
 #include "PDB.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
-#include "lld/Core/Parallel.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/Parallel.h"
 #include "llvm/Support/RandomNumberGenerator.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -745,8 +745,8 @@
     // ADD instructions).
     if (Sec->getPermissions() & IMAGE_SCN_CNT_CODE)
       memset(SecBuf, 0xCC, Sec->getRawSize());
-    for_each(parallel::par, Sec->getChunks().begin(), Sec->getChunks().end(),
-             [&](Chunk *C) { C->writeTo(SecBuf); });
+    for_each(llvm::parallel::par, Sec->getChunks().begin(),
+             Sec->getChunks().end(), [&](Chunk *C) { C->writeTo(SecBuf); });
   }
 }
 
@@ -760,13 +760,13 @@
   uint8_t *End = Begin + Sec->getVirtualSize();
   if (Config->Machine == AMD64) {
     struct Entry { ulittle32_t Begin, End, Unwind; };
-    sort(parallel::par, (Entry *)Begin, (Entry *)End,
+    sort(llvm::parallel::par, (Entry *)Begin, (Entry *)End,
          [](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
     return;
   }
   if (Config->Machine == ARMNT) {
     struct Entry { ulittle32_t Begin, Unwind; };
-    sort(parallel::par, (Entry *)Begin, (Entry *)End,
+    sort(llvm::parallel::par, (Entry *)Begin, (Entry *)End,
          [](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
     return;
   }
Index: lld/ELF/Threads.h
===================================================================
--- lld/ELF/Threads.h
+++ lld/ELF/Threads.h
@@ -61,7 +61,7 @@
 
 #include "Config.h"
 
-#include "lld/Core/Parallel.h"
+#include "llvm/Support/Parallel.h"
 #include <algorithm>
 #include <functional>
 
@@ -71,17 +71,17 @@
 template <class IterTy, class FuncTy>
 void parallelForEach(IterTy Begin, IterTy End, FuncTy Fn) {
   if (Config->Threads)
-    for_each(parallel::par, Begin, End, Fn);
+    for_each(llvm::parallel::par, Begin, End, Fn);
   else
-    for_each(parallel::seq, Begin, End, Fn);
+    for_each(llvm::parallel::seq, Begin, End, Fn);
 }
 
 inline void parallelFor(size_t Begin, size_t End,
                         std::function<void(size_t)> Fn) {
   if (Config->Threads)
-    for_each_n(parallel::par, Begin, End, Fn);
+    for_each_n(llvm::parallel::par, Begin, End, Fn);
   else
-    for_each_n(parallel::seq, Begin, End, Fn);
+    for_each_n(llvm::parallel::seq, Begin, End, Fn);
 }
 }
 }
Index: lld/include/lld/Core/TaskGroup.h
===================================================================
--- lld/include/lld/Core/TaskGroup.h
+++ /dev/null
@@ -1,65 +0,0 @@
-//===- lld/Core/TaskGroup.h - Task Group ----------------------------------===//
-//
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLD_CORE_TASKGROUP_H
-#define LLD_CORE_TASKGROUP_H
-
-#include "lld/Core/LLVM.h"
-
-#include <condition_variable>
-#include <functional>
-#include <mutex>
-
-namespace lld {
-/// \brief Allows one or more threads to wait on a potentially unknown number of
-///   events.
-///
-/// A latch starts at \p count. inc() increments this, and dec() decrements it.
-/// All calls to sync() will block while the count is not 0.
-///
-/// Calling dec() on a Latch with a count of 0 has undefined behaivor.
-class Latch {
-  uint32_t _count;
-  mutable std::mutex _condMut;
-  mutable std::condition_variable _cond;
-
-public:
-  explicit Latch(uint32_t count = 0) : _count(count) {}
-  ~Latch() { sync(); }
-
-  void inc() {
-    std::unique_lock<std::mutex> lock(_condMut);
-    ++_count;
-  }
-
-  void dec() {
-    std::unique_lock<std::mutex> lock(_condMut);
-    if (--_count == 0)
-      _cond.notify_all();
-  }
-
-  void sync() const {
-    std::unique_lock<std::mutex> lock(_condMut);
-    _cond.wait(lock, [&] { return _count == 0; });
-  }
-};
-
-/// \brief Allows launching a number of tasks and waiting for them to finish
-///   either explicitly via sync() or implicitly on destruction.
-class TaskGroup {
-  Latch _latch;
-
-public:
-  void spawn(std::function<void()> f);
-
-  void sync() const { _latch.sync(); }
-};
-}
-
-#endif
Index: lld/lib/Core/CMakeLists.txt
===================================================================
--- lld/lib/Core/CMakeLists.txt
+++ lld/lib/Core/CMakeLists.txt
@@ -12,7 +12,6 @@
   Resolver.cpp
   SymbolTable.cpp
   TargetOptionsCommandFlags.cpp
-  TaskGroup.cpp
   Writer.cpp
 
   ADDITIONAL_HEADER_DIRS
Index: lld/lib/ReaderWriter/MachO/LayoutPass.cpp
===================================================================
--- lld/lib/ReaderWriter/MachO/LayoutPass.cpp
+++ lld/lib/ReaderWriter/MachO/LayoutPass.cpp
@@ -9,12 +9,12 @@
 
 #include "LayoutPass.h"
 #include "lld/Core/Instrumentation.h"
-#include "lld/Core/Parallel.h"
 #include "lld/Core/PassManager.h"
 #include "lld/ReaderWriter/MachOLinkingContext.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Parallel.h"
 #include <algorithm>
 #include <set>
 #include <utility>
@@ -461,7 +461,7 @@
   });
 
   std::vector<LayoutPass::SortKey> vec = decorate(atomRange);
-  sort(parallel::par, vec.begin(), vec.end(),
+  sort(llvm::parallel::par, vec.begin(), vec.end(),
        [&](const LayoutPass::SortKey &l, const LayoutPass::SortKey &r) -> bool {
          return compareAtoms(l, r, _customSorter);
        });
Index: lld/unittests/CMakeLists.txt
===================================================================
--- lld/unittests/CMakeLists.txt
+++ lld/unittests/CMakeLists.txt
@@ -12,6 +12,5 @@
   target_link_libraries(${test_dirname} ${LLVM_COMMON_LIBS})
 endfunction()
 
-add_subdirectory(CoreTests)
 add_subdirectory(DriverTests)
 add_subdirectory(MachOTests)
Index: lld/unittests/CoreTests/CMakeLists.txt
===================================================================
--- lld/unittests/CoreTests/CMakeLists.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-add_lld_unittest(CoreTests
-  ParallelTest.cpp
-  )
-
-target_link_libraries(CoreTests
-  lldCore ${LLVM_PTHREAD_LIB}
-  )
Index: llvm/include/llvm/Support/Parallel.h
===================================================================
--- llvm/include/llvm/Support/Parallel.h
+++ llvm/include/llvm/Support/Parallel.h
@@ -1,29 +1,71 @@
-//===- lld/Core/Parallel.h - Parallel utilities ---------------------------===//
+//===- llvm/Support/Parallel.h - Parallel algorithms ----------------------===//
 //
-//                             The LLVM Linker
+//                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLD_CORE_PARALLEL_H
-#define LLD_CORE_PARALLEL_H
+#ifndef LLVM_SUPPORT_PARALLEL_H
+#define LLVM_SUPPORT_PARALLEL_H
 
-#include "lld/Core/LLVM.h"
-#include "lld/Core/TaskGroup.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/TaskGroup.h"
 
 #include <algorithm>
+#include <condition_variable>
+#include <functional>
+#include <mutex>
 
 #if defined(_MSC_VER) && LLVM_ENABLE_THREADS
+#pragma warning(push)
+#pragma warning(disable : 4530)
 #include <concrt.h>
 #include <ppl.h>
+#pragma warning(pop)
 #endif
 
-namespace lld {
+namespace llvm {
+
+namespace detail {
+class Latch {
+  uint32_t Count;
+  mutable std::mutex Mutex;
+  mutable std::condition_variable Cond;
+
+public:
+  explicit Latch(uint32_t count = 0) : Count(Count) {}
+  ~Latch() { sync(); }
+
+  void inc() {
+    std::unique_lock<std::mutex> lock(Mutex);
+    ++Count;
+  }
+
+  void dec() {
+    std::unique_lock<std::mutex> lock(Mutex);
+    if (--Count == 0)
+      Cond.notify_all();
+  }
+
+  void sync() const {
+    std::unique_lock<std::mutex> lock(Mutex);
+    Cond.wait(lock, [&] { return Count == 0; });
+  }
+};
+
+class TaskGroup {
+  Latch L;
+
+public:
+  void spawn(std::function<void()> f);
+
+  void sync() const { L.sync(); }
+};
+}
 
 namespace parallel {
 struct sequential_execution_policy {};
@@ -204,6 +246,6 @@
 #endif
 
 } // namespace parallel
-} // End namespace lld
+} // namespace llvm
 
-#endif // LLD_CORE_PARALLEL_H
+#endif // LLVM_SUPPORT_PARALLEL_H
Index: llvm/lib/Support/CMakeLists.txt
===================================================================
--- llvm/lib/Support/CMakeLists.txt
+++ llvm/lib/Support/CMakeLists.txt
@@ -81,6 +81,7 @@
   MD5.cpp
   NativeFormatting.cpp
   Options.cpp
+  Parallel.cpp
   PluginLoader.cpp
   PrettyStackTrace.cpp
   RandomNumberGenerator.cpp
Index: llvm/lib/Support/Parallel.cpp
===================================================================
--- llvm/lib/Support/Parallel.cpp
+++ llvm/lib/Support/Parallel.cpp
@@ -1,25 +1,20 @@
-//===- lld/Core/TaskGroup.cpp - Task Group --------------------------------===//
+//===- llvm/Support/Parallel.cpp - Parallel algorithms --------------------===//
 //
-//                             The LLVM Linker
+//                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
-#include "lld/Core/TaskGroup.h"
+#include "llvm/Support/Parallel.h"
 #include "llvm/Config/llvm-config.h"
 
 #include <atomic>
 #include <stack>
 #include <thread>
 
-#if defined(_MSC_VER) && LLVM_ENABLE_THREADS
-#include <concrt.h>
-#include <ppl.h>
-#endif
-
-using namespace lld;
+using namespace llvm;
 
 namespace {
 
@@ -132,10 +127,10 @@
 #endif
 }
 
-void TaskGroup::spawn(std::function<void()> f) {
-  _latch.inc();
+void detail::TaskGroup::spawn(std::function<void()> f) {
+  L.inc();
   Executor::getDefaultExecutor()->add([&, f] {
     f();
-    _latch.dec();
+    L.dec();
   });
 }
Index: llvm/unittests/Support/CMakeLists.txt
===================================================================
--- llvm/unittests/Support/CMakeLists.txt
+++ llvm/unittests/Support/CMakeLists.txt
@@ -36,6 +36,7 @@
   MemoryBufferTest.cpp
   MemoryTest.cpp
   NativeFormatTests.cpp
+  ParallelTest.cpp
   Path.cpp
   ProcessTest.cpp
   ProgramTest.cpp
Index: llvm/unittests/Support/ParallelTest.cpp
===================================================================
--- llvm/unittests/Support/ParallelTest.cpp
+++ llvm/unittests/Support/ParallelTest.cpp
@@ -1,4 +1,4 @@
-//===- lld/unittest/ParallelTest.cpp --------------------------------------===//
+//===- llvm/unittest/Support/ParallelTest.cpp -----------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -12,13 +12,15 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/Parallel.h"
 #include "gtest/gtest.h"
-#include "lld/Core/Parallel.h"
 #include <array>
 #include <random>
 
 uint32_t array[1024 * 1024];
 
+using namespace llvm;
+
 TEST(Parallel, sort) {
   std::mt19937 randEngine;
   std::uniform_int_distribution<uint32_t> dist;
@@ -26,7 +28,7 @@
   for (auto &i : array)
     i = dist(randEngine);
 
-  sort(lld::parallel::par, std::begin(array), std::end(array));
+  sort(parallel::par, std::begin(array), std::end(array));
   ASSERT_TRUE(std::is_sorted(std::begin(array), std::end(array)));
 }
 
@@ -36,7 +38,7 @@
   // writing.
   uint32_t range[2050];
   std::fill(range, range + 2050, 1);
-  for_each_n(lld::parallel::par, 0, 2049, [&range](size_t I) { ++range[I]; });
+  for_each_n(parallel::par, 0, 2049, [&range](size_t I) { ++range[I]; });
 
   uint32_t expected[2049];
   std::fill(expected, expected + 2049, 2);