diff --git a/include/llvm/System/Mutex.h b/include/llvm/System/Mutex.h
new file mode 100644
index 00000000000..16e898c2ded
--- /dev/null
+++ b/include/llvm/System/Mutex.h
@@ -0,0 +1,82 @@
+//===- llvm/System/Mutex.h - Mutex Operating System Concept -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the llvm::sys::Mutex class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_MUTEX_H
+#define LLVM_SYSTEM_MUTEX_H
+
+namespace llvm
+{
+  namespace sys
+  {
+    /// @brief Platform agnostic Mutex class.
+    class Mutex
+    {
+    /// @name Constructors
+    /// @{
+    public:
+
+      /// Initializes the lock but doesn't acquire it. if \p recursive is set
+      /// to false, the lock will not be recursive which makes it cheaper but
+      /// also more likely to deadlock (same thread can't acquire more than
+      /// once).
+      /// @brief Default Constructor.
+      Mutex ( bool recursive = true );
+
+      /// Releases and removes the lock
+      /// @brief Destructor
+      ~Mutex ( void );
+
+    /// @}
+    /// @name Methods
+    /// @{
+    public:
+
+      /// Attempts to unconditionally acquire the lock. If the lock is held by
+      /// another thread, this method will wait until it can acquire the lock.
+      /// @returns false if any kind of error occurs, true otherwise.
+      /// @brief Unconditionally acquire the lock.
+      bool acquire();
+
+      /// Attempts to release the lock. If the lock is held by the current
+      /// thread, the lock is released allowing other threads to acquire the
+      /// lock. 
+      /// @returns false if any kind of error occurs, true otherwise.
+      /// @brief Unconditionally release the lock.
+      bool release(void);
+
+      /// Attempts to acquire the lock without blocking. If the lock is not
+      /// available, this function returns false quickly (without blocking). If
+      /// the lock is available, it is acquired.
+      /// @returns false if any kind of error occurs or the lock is not
+      /// available, true otherwise.
+      /// @brief Try to acquire the lock.
+      bool tryacquire();
+ 
+    //@}
+    /// @name Platform Dependent Data
+    /// @{
+    private:
+        void* data_; ///< We don't know what the data will be
+
+    /// @}
+    /// @name Do Not Implement
+    /// @{
+    private: 
+	Mutex(const Mutex & original);
+	void operator=(const Mutex &);
+    /// @}
+    };
+  }
+}
+
+#endif
diff --git a/lib/System/Mutex.cpp b/lib/System/Mutex.cpp
new file mode 100644
index 00000000000..2a151976913
--- /dev/null
+++ b/lib/System/Mutex.cpp
@@ -0,0 +1,141 @@
+//===- Mutex.cpp - Mutual Exclusion Lock ------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the llvm::sys::Mutex class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/Mutex.h"
+#include "llvm/Config/config.h"
+
+namespace llvm {
+using namespace sys;
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
+#if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_MUTEX_LOCK)
+#include <cassert>
+#include <pthread.h>
+#include <stdlib.h>
+
+// This variable is useful for situations where the pthread library has been
+// compiled with weak linkage for its interface symbols. This allows the 
+// threading support to be turned off by simply not linking against -lpthread.
+// In that situation, the value of pthread_mutex_init will be 0 and 
+// consequently pthread_enabled will be false. In such situations, all the
+// pthread operations become no-ops and the functions all return false. If
+// pthread_mutex_init does have an address, then mutex support is enabled.
+// Note: all LLVM tools will link against -lpthread if its available since it
+//       is configured into the LIBS variable.
+// Note: this line of code generates a warning if pthread_mutex_init is not
+//       declared with weak linkage. Its safe to ignore the warning.
+static const bool pthread_enabled = static_cast<bool>(pthread_mutex_init);
+
+// Construct a Mutex using pthread calls
+Mutex::Mutex( bool recursive)
+  : data_(0)
+{
+  if (pthread_enabled)
+  {
+    // Declare the pthread_mutex data structures
+    pthread_mutex_t* mutex = 
+      static_cast<pthread_mutex_t*>(malloc(sizeof(pthread_mutex_t)));
+    pthread_mutexattr_t attr;
+
+    // Initialize the mutex attributes
+    int errorcode = pthread_mutexattr_init(&attr);
+    assert(errorcode == 0);
+
+    // Initialize the mutex as a recursive mutex, if requested, or normal
+    // otherwise.
+    int kind = ( recursive  ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL );
+    errorcode = pthread_mutexattr_settype(&attr, kind);
+    assert(errorcode == 0);
+
+    // Make it a process local mutex
+    errorcode = pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_PRIVATE);
+
+    // Initialize the mutex
+    errorcode = pthread_mutex_init(mutex, &attr);
+    assert(errorcode == 0);
+
+    // Destroy the attributes
+    errorcode = pthread_mutexattr_destroy(&attr);
+    assert(errorcode == 0);
+
+    // Assign the data member
+    data_ = mutex;
+  }
+}
+
+// Destruct a Mutex
+Mutex::~Mutex()
+{
+  if (pthread_enabled)
+  {
+    pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
+    assert(mutex != 0);
+    int errorcode = pthread_mutex_destroy(mutex);
+    assert(mutex != 0);
+  }
+}
+
+bool 
+Mutex::acquire()
+{
+  if (pthread_enabled) 
+  {
+    pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
+    assert(mutex != 0);
+
+    int errorcode = pthread_mutex_lock(mutex);
+    return errorcode == 0;
+  }
+  return false;
+}
+
+bool 
+Mutex::release()
+{
+  if (pthread_enabled)
+  {
+    pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
+    assert(mutex != 0);
+
+    int errorcode = pthread_mutex_unlock(mutex);
+    return errorcode == 0;
+  }
+  return false;
+}
+
+bool 
+Mutex::tryacquire()
+{
+  if (pthread_enabled)
+  {
+    pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
+    assert(mutex != 0);
+
+    int errorcode = pthread_mutex_trylock(mutex);
+    return errorcode == 0;
+  }
+  return false;
+}
+
+}
+#elif defined(LLVM_ON_UNIX)
+#include "Unix/Mutex.inc"
+#elif defined( LLVM_ON_WIN32)
+#include "Win32/Mutex.inc"
+#else
+#warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in System/Mutex.cpp
+#endif
diff --git a/lib/System/Unix/Mutex.inc b/lib/System/Unix/Mutex.inc
new file mode 100644
index 00000000000..fa218dbb53c
--- /dev/null
+++ b/lib/System/Unix/Mutex.inc
@@ -0,0 +1,46 @@
+//===- llvm/System/Unix/Mutex.inc - Unix Mutex Implementation ---*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the 
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Unix specific (non-pthread) Mutex class.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only generic UNIX code that
+//===          is guaranteed to work on *all* UNIX variants.
+//===----------------------------------------------------------------------===//
+
+namespace llvm
+{
+using namespace sys;
+
+Mutex::Mutex( bool recursive)
+{
+}
+
+Mutex::~Mutex()
+{
+}
+
+bool 
+Mutex::acquire()
+{
+}
+
+bool 
+Mutex::release()
+{
+}
+
+bool 
+Mutex::tryacquire( void )
+{
+}
+
+}
diff --git a/lib/System/Win32/Mutex.inc b/lib/System/Win32/Mutex.inc
new file mode 100644
index 00000000000..d6acb2352be
--- /dev/null
+++ b/lib/System/Win32/Mutex.inc
@@ -0,0 +1,46 @@
+//===- llvm/System/Win32/Mutex.inc - Win32 Mutex Implementation -*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the 
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Win32 specific (non-pthread) Mutex class.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only generic Win32 code that
+//===          is guaranteed to work on *all* Win32 variants.
+//===----------------------------------------------------------------------===//
+
+namespace llvm
+{
+using namespace sys;
+
+Mutex::Mutex( bool recursive)
+{
+}
+
+Mutex::~Mutex()
+{
+}
+
+bool 
+Mutex::acquire()
+{
+}
+
+bool 
+Mutex::release()
+{
+}
+
+bool 
+Mutex::tryacquire( void )
+{
+}
+
+}