diff --git a/lib/Lex/PTHManager.cpp b/lib/Lex/PTHManager.cpp
new file mode 100644
index 0000000..594f55d
--- /dev/null
+++ b/lib/Lex/PTHManager.cpp
@@ -0,0 +1,248 @@
+//===--- PTHManager.cpp - Manager object for PTH processing -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the PTHManager interface.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Lex/PTHManager.h"
+#include "clang/Lex/Token.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/IdentifierTable.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/DenseMap.h"
+
+using namespace clang;
+
+//===----------------------------------------------------------------------===//
+// Utility methods for reading from the mmap'ed PTH file.
+//===----------------------------------------------------------------------===//
+
+static uint8_t Read8(const char*& data) {
+  return (uint8_t) *(data++);
+}
+
+static uint32_t Read32(const char*& data) {
+  uint32_t V = (uint32_t) Read8(data);
+  V |= (((uint32_t) Read8(data)) << 8);
+  V |= (((uint32_t) Read8(data)) << 16);
+  V |= (((uint32_t) Read8(data)) << 24);
+  return V;
+}
+
+//===----------------------------------------------------------------------===//
+// Internal Data Structures.
+//===----------------------------------------------------------------------===//
+
+typedef llvm::DenseMap<uint32_t, IdentifierInfo*> IDCache;
+
+/// PTHFileLookup - This internal data structure is used by the PTHManager
+///  to map from FileEntry objects managed by FileManager to offsets within
+///  the PTH file.
+namespace {
+class VISIBILITY_HIDDEN PTHFileLookup {
+public:
+  class Val {
+    uint32_t v;
+    
+  public:
+    Val() : v(~0) {}
+    Val(uint32_t x) : v(x) {}
+
+    operator uint32_t() const {
+      assert(v != ~((uint32_t)0) && "PTHFileLookup entry initialized.");
+      return v;
+    }
+    
+    Val& operator=(uint32_t x) { v = x; return *this; }
+    bool isValid() const { return v != ~((uint32_t)0); }
+  };
+    
+private:
+  llvm::StringMap<Val> FileMap;
+
+public:
+  PTHFileLookup() {};
+  
+  Val Lookup(const FileEntry* FE) {
+    const char* s = FE->getName();
+    unsigned size = strlen(s);
+    return FileMap.GetOrCreateValue(s, s+size).getValue();
+  }
+  
+  void ReadTable(const char* D) {    
+    uint32_t N = Read32(D);     // Read the length of the table.
+    
+    for ( ; N > 0; --N) {       // The rest of the data is the table itself.
+      uint32_t len = Read32(D);
+      const char* s = D;
+      D += len;
+      FileMap.GetOrCreateValue(s, s+len).getValue() = Read32(D);
+    }
+  }
+};
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// PTHManager methods.
+//===----------------------------------------------------------------------===//
+
+PTHManager::PTHManager(const llvm::MemoryBuffer* buf, void* fileLookup,
+                       const char* idDataTable, Preprocessor& pp)
+  : Buf(buf), PersistentIDCache(0), FileLookup(fileLookup),
+    IdDataTable(idDataTable), ITable(pp.getIdentifierTable()), PP(pp) {}
+
+PTHManager::~PTHManager() {
+  delete Buf;
+  delete (PTHFileLookup*) FileLookup;
+  delete (IDCache*) PersistentIDCache;
+}
+
+PTHManager* PTHManager::Create(const std::string& file, Preprocessor& PP) {
+
+  // Memory map the PTH file.
+  llvm::OwningPtr<llvm::MemoryBuffer>
+    File(llvm::MemoryBuffer::getFile(file.c_str()));
+
+  if (!File)
+    return 0;
+
+  // Get the buffer ranges and check if there are at least three 32-bit
+  // words at the end of the file.
+  const char* BufBeg = File->getBufferStart();
+  const char* BufEnd = File->getBufferEnd();
+  
+  if(!(BufEnd > BufBeg + sizeof(uint32_t)*3)) {
+    assert(false && "Invalid PTH file.");
+    return 0; // FIXME: Proper error diagnostic?
+  }
+
+  // Compute the address of the index table at the end of the PTH file.
+  // This table contains the offset of the file lookup table, the
+  // persistent ID -> identifer data table.
+  const char* EndTable = BufEnd - sizeof(uint32_t)*3;
+
+  // Construct the file lookup table.  This will be used for mapping from
+  // FileEntry*'s to cached tokens.
+  const char* FileTableOffset = EndTable + sizeof(uint32_t)*2;
+  const char* FileTable = BufBeg + Read32(FileTableOffset);
+  
+  if (!(FileTable > BufBeg && FileTable < BufEnd)) {
+    assert(false && "Invalid PTH file.");
+    return 0; // FIXME: Proper error diagnostic?
+  }
+  
+  llvm::OwningPtr<PTHFileLookup> FL(new PTHFileLookup());
+  FL->ReadTable(FileTable);
+
+  // Get the location of the table mapping from persistent ids to the
+  // data needed to reconstruct identifiers.
+  const char* IDTableOffset = EndTable + sizeof(uint32_t)*1;
+  const char* IData = BufBeg + Read32(IDTableOffset);
+  if (!(IData > BufBeg && IData < BufEnd)) {
+    assert(false && "Invalid PTH file.");
+    return 0; // FIXME: Proper error diagnostic?
+  }
+
+  return new PTHManager(File.take(), FL.take(), IData, PP);
+}
+
+IdentifierInfo* PTHManager::ReadIdentifierInfo(const char*& D) {
+  // Read the persistent ID from the PTH file.
+  uint32_t persistentID = Read32(D);
+
+  // A persistent ID of '0' always maps to NULL.
+  if (!persistentID)
+    return 0;
+  
+  // Adjust the persistent ID by subtracting '1' so that it can be used
+  // as an index within a table in the PTH file.
+  --persistentID;
+  
+  // Check if the IdentifierInfo has already been resolved.
+  if (!PersistentIDCache)
+    PersistentIDCache = new IDCache();
+
+  // FIXME: We can make this an array, but what is the performance tradeoff?
+  IdentifierInfo*& II = (*((IDCache*) PersistentIDCache))[persistentID];
+  if (II) return II;
+
+  // Look in the PTH file for the string data for the IdentifierInfo object.
+  const char* TableEntry = IdDataTable + sizeof(uint32_t) * persistentID;
+  const char* IDData = Buf->getBufferStart() + Read32(TableEntry);
+  assert(IDData < Buf->getBufferEnd());
+
+  // Read the length of the string.
+  uint32_t len = Read32(IDData);  
+  
+  // Get the IdentifierInfo* with the specified string.
+  II = &ITable.get(IDData, IDData+len);
+  return II;
+}
+
+void PTHManager::ReadToken(const char*& D, unsigned FileID, Token& T) {
+  // Clear the token.
+  // FIXME: Setting the flags directly should obviate this step.
+  T.startToken();
+  
+  // Read the type of the token.
+  T.setKind((tok::TokenKind) Read8(D));
+
+  // Set flags.  This is gross, since we are really setting multiple flags.
+  T.setFlag((Token::TokenFlags) Read8(D));
+  
+  // Set the IdentifierInfo* (if any).
+  T.setIdentifierInfo(ReadIdentifierInfo(D));
+  
+  // Set the SourceLocation.  Since all tokens are constructed using a
+  // raw lexer, they will all be offseted from the same FileID.
+  T.setLocation(SourceLocation::getFileLoc(FileID, Read32(D)));
+
+  // Finally, read and set the length of the token.
+  T.setLength(Read32(D));
+}
+
+PTHLexer* PTHManager::CreateLexer(unsigned FileID, const FileEntry* FE) {
+  
+  if (!FE)
+    return 0;
+  
+  // Lookup the FileEntry object in our file lookup data structure.  It will
+  // return a variant that indicates whether or not there is an offset within
+  // the PTH file that contains cached tokens.
+  PTHFileLookup::Val Off = ((PTHFileLookup*) FileLookup)->Lookup(FE);
+
+  if (!Off.isValid()) // No tokens available.
+    return 0;
+
+  // Compute the offset of the token data within the buffer.
+  const char* data = Buf->getBufferStart() + Off;
+  assert(data < Buf->getBufferEnd());
+  
+  // First cut: read the tokens from the file into a vector.
+  // Later, stream them.  
+  SourceLocation Loc = SourceLocation::getFileLoc(FileID, 0);
+  llvm::OwningPtr<PTHLexer> L(new PTHLexer(PP, Loc));
+  std::vector<Token>& Tokens = L->getTokens();
+  
+  Token T;
+  do {
+    ReadToken(data, FileID, T);
+    Tokens.push_back(T);
+  }
+  while (T.isNot(tok::eof));
+
+  // Return the lexer to the client.  The client assumes ownership of this
+  // PTHLexer object.
+  return L.take();
+}