diff --git a/llvm/include/Support/ThreadSupport-NoSupport.h b/llvm/include/Support/ThreadSupport-NoSupport.h
new file mode 100644
index 000000000000..5dc954efab1d
--- /dev/null
+++ b/llvm/include/Support/ThreadSupport-NoSupport.h
@@ -0,0 +1,34 @@
+//===-- Support/ThreadSupport-NoSupport.h - Generic impl --------*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file defines a generic ThreadSupport implementation used when there is
+// no supported threading mechanism on the current system.  Users should never
+// #include this file directly!
+//
+//===----------------------------------------------------------------------===//
+
+// Users should never #include this file directly!  As such, no include guards
+// are needed.
+
+#ifndef SUPPORT_THREADSUPPORT_H
+#error "Code should not #include Support/ThreadSupport-NoSupport.h directly!"
+#endif
+
+namespace llvm {
+  /// Mutex - This class allows user code to protect variables shared between
+  /// threads.  It implements a "recursive" mutex, to simplify user code.
+  ///
+  /// Since there is no platform support for _creating threads_, the non-thread
+  /// implementation of this class is a noop.
+  ///
+  struct Mutex {
+    void acquire () {}
+    void release () {}
+  };
+}
diff --git a/llvm/include/Support/ThreadSupport-PThreads.h b/llvm/include/Support/ThreadSupport-PThreads.h
index 2fcbe72a81c8..6bbe682c0896 100644
--- a/llvm/include/Support/ThreadSupport-PThreads.h
+++ b/llvm/include/Support/ThreadSupport-PThreads.h
@@ -1,4 +1,4 @@
-//===-- Support/Lock.h - Platform-agnostic mutual exclusion -----*- C++ -*-===//
+//===-- Support/ThreadSupport-PThreads.h - PThreads support -----*- C++ -*-===//
 // 
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,63 +7,36 @@
 // 
 //===----------------------------------------------------------------------===//
 //
-// This file contains classes that implement locks (mutual exclusion
-// variables) in a platform-agnostic way. Basically the user should
-// just call Lock::create() to get a Lock object of the correct sort
-// for the current platform, and use its acquire() and release()
-// methods, or a LockHolder, to protect critical sections of code for
-// thread-safety.
+// This file defines pthreads implementations of the generic threading
+// mechanisms.  Users should never #include this file directly!
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef SUPPORT_LOCK_H
-#define SUPPORT_LOCK_H
+// Users should never #include this file directly!  As such, no include guards
+// are needed.
+
+#ifndef SUPPORT_THREADSUPPORT_H
+#error "Code should not #include Support/ThreadSupport/PThreads.h directly!"
+#endif
 
 #include <pthread.h>
-#include <cstdlib>
 
 namespace llvm {
 
-/// Lock - Abstract class that provides mutual exclusion (also known
-/// as a mutex.)
-///
-class Lock {
-protected:
-  virtual ~Lock() {}                        // Derive from me
-public:
-  virtual void acquire () { abort (); }
-  virtual void release () { abort (); }
-
-  /// create - Static method that returns a Lock of the correct class
-  /// for the current host OS.
+  /// Mutex - This class allows user code to protect variables shared between
+  /// threads.  It implements a "recursive" mutex, to simplify user code.
   ///
-  static Lock create ();
-};
-
-/// POSIXLock - Specialization of Lock class implemented using
-/// pthread_mutex_t objects.
-///
-class POSIXLock : public Lock {
-  pthread_mutex_t mutex;
-public:
-  POSIXLock () { pthread_mutex_init (&mutex, 0); }
-  virtual ~POSIXLock () { pthread_mutex_destroy (&mutex); }
-  virtual void acquire () { pthread_mutex_lock (&mutex); }
-  virtual void release () { pthread_mutex_unlock (&mutex); }
-};
-
-/// LockHolder - Instances of this class acquire a given Lock when
-/// constructed and hold that lock until destruction.  Uncle Bjarne
-/// says, "Resource acquisition is allocation." Or is it the other way
-/// around? I never can remember.
-///
-class LockHolder {
-  Lock &L;
-public:
-  LockHolder (Lock &_L) : L (_L) { L.acquire (); }
-  ~LockHolder () { L.release (); }
-};
-
+  class Mutex {
+    pthread_mutex_t mutex;
+    Mutex(const Mutex &);           // DO NOT IMPLEMENT
+    void operator=(const Mutex &);  // DO NOT IMPLEMENT
+  public:
+    Mutex() {
+      pthread_mutexattr_t Attr;
+      pthread_mutex_init(&mutex, &Attr);
+    }
+    ~Mutex() { pthread_mutex_destroy(&mutex); }
+    void acquire () { pthread_mutex_lock (&mutex); }
+    void release () { pthread_mutex_unlock (&mutex); }
+  };
 } // end namespace llvm
-
-#endif // SUPPORT_LOCK_H
diff --git a/llvm/include/Support/ThreadSupport.h b/llvm/include/Support/ThreadSupport.h
new file mode 100644
index 000000000000..1a5f005f7ced
--- /dev/null
+++ b/llvm/include/Support/ThreadSupport.h
@@ -0,0 +1,41 @@
+//===-- Support/ThreadSupport.h - Generic threading support -----*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file defines platform-agnostic interfaces that can be used to write
+// multi-threaded programs.  Autoconf is used to chose the correct
+// implementation of these interfaces, or default to a non-thread-capable system
+// if no matching system support is available.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUPPORT_THREADSUPPORT_H
+#define SUPPORT_THREADSUPPORT_H
+
+// FIXME: We need autoconf support to detect pthreads!
+#if 0
+#include "Support/ThreadSupport-PThreads.h"
+#else
+#include "Support/ThreadSupport-NoSupport.h"
+#endif // If no system support is available
+
+namespace llvm {
+  /// LockHolder - Instances of this class acquire a given Lock when constructed
+  /// and hold that lock until destruction.
+  ///
+  class MutexLocker {
+    Mutex &M;
+    MutexLocker(const LockHolder &);    // DO NOT IMPLEMENT
+    void operator=(const MutexLocker&); // DO NOT IMPLEMENT
+  public:
+    MutexLocker(Mutex &m) : M(m) { M.acquire(); }
+    ~MutexLocker() { M.release(); }
+  };
+}
+
+#endif // SUPPORT_THREADSUPPORT_H