diff --git a/include/llvm/System/MappedFile.h b/include/llvm/System/MappedFile.h
new file mode 100644
index 00000000000..3aa1840319b
--- /dev/null
+++ b/include/llvm/System/MappedFile.h
@@ -0,0 +1,160 @@
+//===- llvm/System/MappedFile.h - MappedFile OS 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::MappedFile class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_MAPPEDFILE_H
+#define LLVM_SYSTEM_MAPPEDFILE_H
+
+#include "llvm/System/Path.h"
+
+namespace llvm {
+namespace sys {
+
+  /// Forward declare a class used for holding platform specific information
+  /// that needs to be 
+  class MappedFileInfo;
+
+  /// This class provides an abstraction for a memory mapped file in the 
+  /// operating system's filesystem. It provides platform independent operations
+  /// for mapping a file into memory for both read and write access. This class
+  /// does not provide facilities for finding the file or operating on paths to
+  /// files. The sys::Path class is used for that. 
+  /// @since 1.4
+  /// @brief An abstraction for memory mapped files.
+  class MappedFile {
+  /// @name Types
+  /// @{
+  public:
+    enum MappingOptions {
+      READ_ACCESS = 0x0001,     ///< Map the file for reading
+      WRITE_ACCESS = 0x0002,    ///< Map the file for write access
+      EXEC_ACCESS = 0x0004,     ///< Map the file for execution access
+      SHARED_MAPPING = 0x0008,  ///< Map the file shared with other processes
+    };
+  /// @}
+  /// @name Constructors
+  /// @{
+  public:
+    /// Construct a MappedFile to the \p path in the operating system's file
+    /// system with the mapping \p options provided.
+    /// @throws std::string if an error occurs
+    MappedFile(const Path& path, int options = READ_ACCESS)
+      : path_(path), options_(options), base_(0), info_(0) {
+      initialize();
+    }
+
+    /// Destruct a MappedFile and release all memory associated with it.
+    /// @throws std::string if an error occurs
+    ~MappedFile() {
+      terminate();
+      path_.clear();
+    }
+
+  /// @}
+  /// @name Accessors
+  /// @{
+  public:
+    /// This function determines if the file is currently mapped or not.
+    /// @returns true iff the file is mapped into memory, false otherwise
+    /// @brief Determine if a MappedFile is currently mapped
+    /// @throws nothing
+    bool isMapped() const { return base_ != 0; }
+
+    /// This function returns a void* pointer to the base address of the file
+    /// mapping. This is the memory address of the first byte in the file.
+    /// Note that although a non-const pointer is returned, the memory might
+    /// not actually be writable, depending on the MappingOptions used when
+    /// the MappedFile was opened.
+    /// @returns The base pointer to the memory mapped file.
+    /// @brief Obtain the base pointer to the memory mapped file.
+    /// @throws nothing
+    void* base() const { return base_; }
+
+    /// This function returns a char* pointer to the base address of the file
+    /// mapping. This is the memory address of the first byte in the file.
+    /// Note that although a non-const pointer is returned, the memory might
+    /// not actually be writable, depending on the MappingOptions used when
+    /// the MappedFile was opened.
+    /// @returns The base pointer to the memory mapped file as a char pointer.
+    /// @brief Obtain the base pointer to the memory mapped file.
+    /// @throws nothing
+    char* charBase() const { return reinterpret_cast<char*>(base_); }
+
+    /// This function returns a reference to the sys::Path object kept by the
+    /// MappedFile object. This contains the path to the file that is or 
+    /// will be mapped.
+    /// @returns sys::Path containing the path name.
+    /// @brief Returns the mapped file's path as a sys::Path
+    /// @throws nothing
+    const sys::Path& path() const { return path_; }
+
+    /// This function returns the number of bytes in the file. 
+    /// @throws std::string if an error occurs
+    size_t size();
+
+  /// @}
+  /// @name Mutators
+  /// @{
+  public:
+    /// The mapped file is removed from memory. If the file was mapped for
+    /// write access, the memory contents will be automatically synchronized
+    /// with the file's disk contents.
+    /// @brief Remove the file mapping from memory.
+    void unmap();
+
+    /// The mapped file is put into memory. 
+    /// @returns The base memory address of the mapped file.
+    /// @brief Map the file into memory.
+    void* map();
+
+    /// This method causes the size of the file, and consequently the size
+    /// of the mapping to be set. This is logically the same as unmap(), 
+    /// adjust size of the file, map(). Consequently, when calling this 
+    /// function, the caller should not rely on previous results of the 
+    /// map(), base(), or baseChar() members as they may point to invalid
+    /// areas of memory after this call.
+    /// @throws std::string if an error occurs
+    /// @brief Set a full path from a std::string
+    void size(size_t new_size);
+
+  /// @}
+  /// @name Implementation
+  /// @{
+  private:
+    void initialize(); ///< Initialize platform-specific portion
+    void terminate();  ///< Terminate platform-specific portion
+
+  /// @}
+  /// @name Data
+  /// @{
+  private:
+    sys::Path path_;       ///< Path to the file.
+    int options_;          ///< Options used to create the mapping
+    void* base_;           ///< Pointer to the base memory address
+    MappedFileInfo* info_; ///< Platform specific info for the mapping
+
+  /// @}
+  /// @name Deprecated
+  /// @{
+  private:
+    ///< Disallow assignment
+    MappedFile& operator = ( const MappedFile & that );
+    ///< Disallow copying
+    MappedFile(const MappedFile& that);
+  /// @}
+  };
+}
+}
+
+// vim: sw=2
+
+#endif
diff --git a/lib/System/AIX/MappedFile.cpp b/lib/System/AIX/MappedFile.cpp
new file mode 100644
index 00000000000..946ebad20d7
--- /dev/null
+++ b/lib/System/AIX/MappedFile.cpp
@@ -0,0 +1,17 @@
+//===- AIX/MappedFile.cpp - AIX MappedFile 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 provides the AIX specific implementation of the MappedFile concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Cygwin/MappedFile.cpp b/lib/System/Cygwin/MappedFile.cpp
new file mode 100644
index 00000000000..09a05757fbe
--- /dev/null
+++ b/lib/System/Cygwin/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- Cygwin/MappedFile.cpp - Cygwin MappedFile 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 provides the Cygwin specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Darwin/MappedFile.cpp b/lib/System/Darwin/MappedFile.cpp
new file mode 100644
index 00000000000..c3f26566d6d
--- /dev/null
+++ b/lib/System/Darwin/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- Darwin/MappedFile.cpp - Darwin MappedFile 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 provides the Darwin specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/FreeBSD/MappedFile.cpp b/lib/System/FreeBSD/MappedFile.cpp
new file mode 100644
index 00000000000..a06691966b8
--- /dev/null
+++ b/lib/System/FreeBSD/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- FreeBSD/MappedFile.cpp - FreeBSD MappedFile Impl. --------*- 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 provides the FreeBSD specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Interix/MappedFile.cpp b/lib/System/Interix/MappedFile.cpp
new file mode 100644
index 00000000000..1600ea4bcae
--- /dev/null
+++ b/lib/System/Interix/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- Interix/MappedFile.cpp - Interix MappedFile Impl. --------*- 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 provides the Interix specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Linux/MappedFile.cpp b/lib/System/Linux/MappedFile.cpp
new file mode 100644
index 00000000000..d8fb35eccb0
--- /dev/null
+++ b/lib/System/Linux/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- Linux/MappedFile.cpp - Linux MappedFile 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 provides the Linux specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/MappedFile.cpp b/lib/System/MappedFile.cpp
new file mode 100644
index 00000000000..55e17012f39
--- /dev/null
+++ b/lib/System/MappedFile.cpp
@@ -0,0 +1,29 @@
+//===- MappedFile.cpp - MappedFile Support ----------------------*- 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 mapped file concept.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/MappedFile.h"
+
+namespace llvm {
+using namespace sys;
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code. 
+//===----------------------------------------------------------------------===//
+
+}
+
+// Include the platform-specific parts of this class.
+#include "platform/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/SunOS/MappedFile.cpp b/lib/System/SunOS/MappedFile.cpp
new file mode 100644
index 00000000000..ebde62afc17
--- /dev/null
+++ b/lib/System/SunOS/MappedFile.cpp
@@ -0,0 +1,18 @@
+//===- SunOS/MappedFile.cpp - SunOS MappedFile 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 provides the SunOS specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+// Include the generic unix implementation
+#include "../Unix/MappedFile.cpp"
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Unix/MappedFile.cpp b/lib/System/Unix/MappedFile.cpp
new file mode 100644
index 00000000000..d853acec4f4
--- /dev/null
+++ b/lib/System/Unix/MappedFile.cpp
@@ -0,0 +1,138 @@
+//===- Unix/MappedFile.cpp - Unix MappedFile 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 provides the generic Unix implementation of the MappedFile concept.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only generic UNIX code that
+//===          is guaranteed to work on *all* UNIX variants.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/Process.h"
+#include "Unix.h"
+#include <sys/fcntl.h>
+#include <sys/mman.h>
+
+namespace llvm {
+using namespace sys;
+
+struct sys::MappedFileInfo {
+  int fd_;
+  struct stat sbuf_;
+};
+
+void MappedFile::initialize() {
+  if (path_.exists()) {
+    info_ = new MappedFileInfo;
+    int mode = 0;
+    if (options_&READ_ACCESS) 
+      if (options_&WRITE_ACCESS)
+        mode = O_RDWR;
+      else
+        mode = O_RDONLY;
+    else if (options_&WRITE_ACCESS)
+      mode = O_WRONLY;
+    info_->fd_ = ::open(path_.c_str(),mode);
+    if (info_->fd_ < 0) {
+      delete info_;
+      info_ = 0;
+      ThrowErrno(std::string("Can't open file: ") + path_.get());
+    }
+    struct stat sbuf;
+    if(::fstat(info_->fd_, &info_->sbuf_) < 0) {
+      ::close(info_->fd_);
+      delete info_;
+      info_ = 0;
+      ThrowErrno(std::string("Can't stat file: ") + path_.get());
+    }
+  }
+}
+
+void MappedFile::terminate() {
+  assert(info_ && "MappedFile not initialized");
+  if (info_->fd_ >= 0)
+    ::close(info_->fd_);
+  delete info_;
+  info_ = 0;
+}
+
+void MappedFile::unmap() {
+  assert(info_ && "MappedFile not initialized");
+  if (isMapped()) {
+    if (options_ & WRITE_ACCESS)
+      ::msync(base_, info_->sbuf_.st_size, MS_SYNC);
+    ::munmap(base_, info_->sbuf_.st_size);
+  }
+}
+
+void* MappedFile::map() {
+  if (!isMapped()) {
+    int prot = PROT_NONE;
+    int flags = MAP_FILE;
+    if (options_ == 0) {
+      prot = PROT_READ;
+      flags = MAP_PRIVATE;
+    } else {
+      if (options_ & READ_ACCESS)
+        prot |= PROT_READ;
+      if (options_ & WRITE_ACCESS)
+        prot |= PROT_WRITE;
+      if (options_ & EXEC_ACCESS)
+        prot |= PROT_EXEC;
+      if (options_ & SHARED_MAPPING)
+        flags |= MAP_SHARED;
+      else
+        flags |= MAP_PRIVATE;
+    }
+    size_t map_size = ((info_->sbuf_.st_size / Process::GetPageSize())+1) *
+      Process::GetPageSize();
+
+    base_ = ::mmap(0, map_size, prot, flags, info_->fd_, 0);
+    if (base_ == MAP_FAILED)
+      ThrowErrno(std::string("Can't map file:") + path_.get());
+  }
+  return base_;
+}
+
+size_t MappedFile::size() {
+  assert(info_ && "MappedFile not initialized");
+  return info_->sbuf_.st_size;
+}
+
+void MappedFile::size(size_t new_size) {
+  assert(info_ && "MappedFile not initialized");
+
+  // Take the mapping out of memory
+  this->unmap();
+
+  // Adjust the current size to a page boundary
+  size_t cur_size = ((info_->sbuf_.st_size / Process::GetPageSize())+1) *
+    Process::GetPageSize();
+
+  // Adjust the new_size to a page boundary
+  new_size = ((new_size / Process::GetPageSize())+1) *
+    Process::GetPageSize();
+
+  // If the file needs to be extended
+  if (new_size > cur_size) {
+    // Ensure we can allocate at least the idodes necessary to handle the
+    // file size requested. 
+    ::lseek(info_->fd_, new_size, SEEK_SET);
+    ::write(info_->fd_, "\0", 1);
+  }
+
+  // Seek to current end of file. 
+  this->map();
+}
+
+}
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab
diff --git a/lib/System/Win32/MappedFile.cpp b/lib/System/Win32/MappedFile.cpp
new file mode 100644
index 00000000000..d106eb16ad2
--- /dev/null
+++ b/lib/System/Win32/MappedFile.cpp
@@ -0,0 +1,38 @@
+//===- Win32/MappedFile.cpp - Win32 MappedFile 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 provides the Win32 specific implementation of the MappedFile
+// concept.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Win32.h"
+
+void MappedFile::initialize() {
+}
+
+void MappedFile::terminate() {
+}
+
+void MappedFile::unmap() {
+}
+
+void* MappedFile::map() {
+  static char junk[4096];
+  return junk;
+}
+
+size_t MappedFile::size() {
+  return 4096;
+}
+
+void MappedFile::size(size_t new_size) {
+}
+
+// vim: sw=2 smartindent smarttab tw=80 autoindent expandtab