Index: include/llvm-c/Core.h
===================================================================
--- include/llvm-c/Core.h
+++ include/llvm-c/Core.h
@@ -2848,16 +2848,13 @@
  * @{
  */
 
-/** Allocate and initialize structures needed to make LLVM safe for
-    multithreading. The return value indicates whether multithreaded
-    initialization succeeded. Must be executed in isolation from all
-    other LLVM api calls.
-    @see llvm::llvm_start_multithreaded */
+/** Deprecated: Multi-threading can only be enabled/disabled with the compile
+    time define LLVM_ENABLE_THREADS.  This function always returns
+    LLVMIsMultithreaded(). */
 LLVMBool LLVMStartMultithreaded(void);
 
-/** Deallocate structures necessary to make LLVM safe for multithreading.
-    Must be executed in isolation from all other LLVM api calls.
-    @see llvm::llvm_stop_multithreaded */
+/** Deprecated: Multi-threading can only be enabled/disabled with the compile
+    time define LLVM_ENABLE_THREADS. */
 void LLVMStopMultithreaded(void);
 
 /** Check whether LLVM is executing in thread-safe mode or not.
Index: include/llvm/Support/ManagedStatic.h
===================================================================
--- include/llvm/Support/ManagedStatic.h
+++ include/llvm/Support/ManagedStatic.h
@@ -103,9 +103,6 @@
 /// llvm_shutdown() when it is destroyed.
 struct llvm_shutdown_obj {
   llvm_shutdown_obj() { }
-  explicit llvm_shutdown_obj(bool multithreaded) {
-    if (multithreaded) llvm_start_multithreaded();
-  }
   ~llvm_shutdown_obj() { llvm_shutdown(); }
 };
 
Index: include/llvm/Support/Threading.h
===================================================================
--- include/llvm/Support/Threading.h
+++ include/llvm/Support/Threading.h
@@ -7,7 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// TThis file defines llvm_start_multithreaded() and friends.
+// This file defines helper functions for running LLVM in a multi-threaded
+// environment.
 //
 //===----------------------------------------------------------------------===//
 
@@ -18,24 +19,10 @@
 
 namespace llvm {
   /// llvm_get_global_lock - returns the llvm global lock object.
-  sys::Mutex& llvm_get_global_lock();
+  sys::Mutex &llvm_get_global_lock();
 
-  /// llvm_start_multithreaded - Allocate and initialize structures needed to
-  /// make LLVM safe for multithreading.  The return value indicates whether
-  /// multithreaded initialization succeeded.  LLVM will still be operational
-  /// on "failed" return, and will still be safe for hosting threading
-  /// applications in the JIT, but will not be safe for concurrent calls to the
-  /// LLVM APIs.
-  /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
-  bool llvm_start_multithreaded();
-
-  /// llvm_stop_multithreaded - Deallocate structures necessary to make LLVM
-  /// safe for multithreading.
-  /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
-  void llvm_stop_multithreaded();
-
-  /// llvm_is_multithreaded - Check whether LLVM is executing in thread-safe
-  /// mode or not.
+  /// llvm_is_multithreaded - returns true if LLVM is compiled with support
+  /// for multiple threads, and false otherwise.
   bool llvm_is_multithreaded();
 
   /// llvm_execute_on_thread - Execute the given \p UserFn on a separate
Index: lib/IR/Core.cpp
===================================================================
--- lib/IR/Core.cpp
+++ lib/IR/Core.cpp
@@ -2702,11 +2702,10 @@
 /*===-- Threading ------------------------------------------------------===*/
 
 LLVMBool LLVMStartMultithreaded() {
-  return llvm_start_multithreaded();
+  return LLVMIsMultithreaded();
 }
 
 void LLVMStopMultithreaded() {
-  llvm_stop_multithreaded();
 }
 
 LLVMBool LLVMIsMultithreaded() {
Index: lib/Support/ManagedStatic.cpp
===================================================================
--- lib/Support/ManagedStatic.cpp
+++ lib/Support/ManagedStatic.cpp
@@ -76,6 +76,4 @@
 void llvm::llvm_shutdown() {
   while (StaticList)
     StaticList->destroy();
-
-  if (llvm_is_multithreaded()) llvm_stop_multithreaded();
 }
Index: lib/Support/Threading.cpp
===================================================================
--- lib/Support/Threading.cpp
+++ lib/Support/Threading.cpp
@@ -7,7 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file implements llvm_start_multithreaded() and friends.
+// This file implements helper functions for running LLVM in a multi-threaded
+// environment.
 //
 //===----------------------------------------------------------------------===//
 
@@ -19,43 +20,19 @@
 
 using namespace llvm;
 
-static bool multithreaded_mode = false;
-
 sys::Mutex& llvm::llvm_get_global_lock() {
   static sys::Mutex global_lock;
   return global_lock;
 }
 
-bool llvm::llvm_start_multithreaded() {
+bool llvm::llvm_is_multithreaded() {
 #if LLVM_ENABLE_THREADS != 0
-  assert(!multithreaded_mode && "Already multithreaded!");
-  multithreaded_mode = true;
-
-  // We fence here to ensure that all initialization is complete BEFORE we
-  // return from llvm_start_multithreaded().
-  sys::MemoryFence();
   return true;
 #else
   return false;
 #endif
 }
 
-void llvm::llvm_stop_multithreaded() {
-#if LLVM_ENABLE_THREADS != 0
-  assert(multithreaded_mode && "Not currently multithreaded!");
-
-  // We fence here to insure that all threaded operations are complete BEFORE we
-  // return from llvm_stop_multithreaded().
-  sys::MemoryFence();
-
-  multithreaded_mode = false;
-#endif
-}
-
-bool llvm::llvm_is_multithreaded() {
-  return multithreaded_mode;
-}
-
 #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
 #include <pthread.h>
 
Index: lib/Support/Timer.cpp
===================================================================
--- lib/Support/Timer.cpp
+++ lib/Support/Timer.cpp
@@ -18,7 +18,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/ManagedStatic.h"
-#include "llvm/support/MutexGuard.h"
+#include "llvm/Support/MutexGuard.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
Index: unittests/Support/ManagedStatic.cpp
===================================================================
--- unittests/Support/ManagedStatic.cpp
+++ unittests/Support/ManagedStatic.cpp
@@ -47,7 +47,6 @@
   void *p1 = test1::allocate_stack(a1);
   void *p2 = test1::allocate_stack(a2);
 
-  llvm_start_multithreaded();
   pthread_t t1, t2;
   pthread_create(&t1, &a1, test1::helper, nullptr);
   pthread_create(&t2, &a2, test1::helper, nullptr);
@@ -55,7 +54,6 @@
   pthread_join(t2, nullptr);
   free(p1);
   free(p2);
-  llvm_stop_multithreaded();
 }
 #endif