Index: llvm/trunk/include/llvm/Bitcode/BitcodeReader.h
===================================================================
--- llvm/trunk/include/llvm/Bitcode/BitcodeReader.h
+++ llvm/trunk/include/llvm/Bitcode/BitcodeReader.h
@@ -66,7 +66,9 @@
                   bool ShouldLazyLoadMetadata);
 
   public:
-    ArrayRef<uint8_t> getBuffer() const { return Buffer; }
+    StringRef getBuffer() const {
+      return StringRef((const char *)Buffer.begin(), Buffer.size());
+    }
 
     /// Read the bitcode module and prepare for lazy deserialization of function
     /// bodies. If ShouldLazyLoadMetadata is true, lazily load metadata as well.
Index: llvm/trunk/test/CMakeLists.txt
===================================================================
--- llvm/trunk/test/CMakeLists.txt
+++ llvm/trunk/test/CMakeLists.txt
@@ -48,6 +48,7 @@
           llvm-lto2
           llvm-mc
           llvm-mcmarkup
+          llvm-modextract
           llvm-nm
           llvm-objdump
           llvm-opt-report
Index: llvm/trunk/test/lit.cfg
===================================================================
--- llvm/trunk/test/lit.cfg
+++ llvm/trunk/test/lit.cfg
@@ -298,6 +298,7 @@
                 r"\bllvm-lto2\b",
                 r"\bllvm-mc\b",
                 r"\bllvm-mcmarkup\b",
+                r"\bllvm-modextract\b",
                 r"\bllvm-nm\b",
                 r"\bllvm-objdump\b",
                 r"\bllvm-pdbdump\b",
Index: llvm/trunk/test/tools/llvm-modextract/single.ll
===================================================================
--- llvm/trunk/test/tools/llvm-modextract/single.ll
+++ llvm/trunk/test/tools/llvm-modextract/single.ll
@@ -0,0 +1,12 @@
+; RUN: llvm-as -o %t %s
+; RUN: llvm-modextract -n 0 -o - %t | llvm-dis | FileCheck %s
+; RUN: not llvm-modextract -n 1 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
+; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck %s
+; RUN: not llvm-modextract -b -n 1 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
+
+; CHECK: define void @f()
+; ERROR: llvm-modextract: error: module index out of range; bitcode file contains 1 module(s)
+
+define void @f() {
+  ret void
+}
Index: llvm/trunk/tools/LLVMBuild.txt
===================================================================
--- llvm/trunk/tools/LLVMBuild.txt
+++ llvm/trunk/tools/LLVMBuild.txt
@@ -36,6 +36,7 @@
  llvm-lto
  llvm-mc
  llvm-mcmarkup
+ llvm-modextract
  llvm-nm
  llvm-objdump
  llvm-pdbdump
Index: llvm/trunk/tools/llvm-modextract/CMakeLists.txt
===================================================================
--- llvm/trunk/tools/llvm-modextract/CMakeLists.txt
+++ llvm/trunk/tools/llvm-modextract/CMakeLists.txt
@@ -0,0 +1,10 @@
+set(LLVM_LINK_COMPONENTS
+  IRReader
+  BitWriter
+  Core
+  Support
+  )
+
+add_llvm_tool(llvm-modextract
+  llvm-modextract.cpp
+  )
Index: llvm/trunk/tools/llvm-modextract/LLVMBuild.txt
===================================================================
--- llvm/trunk/tools/llvm-modextract/LLVMBuild.txt
+++ llvm/trunk/tools/llvm-modextract/LLVMBuild.txt
@@ -0,0 +1,22 @@
+;===- ./tools/llvm-modextract/LLVMBuild.txt --------------------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Tool
+name = llvm-modextract
+parent = Tools
+required_libraries = BitReader BitWriter
Index: llvm/trunk/tools/llvm-modextract/llvm-modextract.cpp
===================================================================
--- llvm/trunk/tools/llvm-modextract/llvm-modextract.cpp
+++ llvm/trunk/tools/llvm-modextract/llvm-modextract.cpp
@@ -0,0 +1,72 @@
+//===-- llvm-modextract.cpp - LLVM module extractor utility ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This program is for testing features that rely on multi-module bitcode files.
+// It takes a multi-module bitcode file, extracts one of the modules and writes
+// it to the output file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/BitcodeReader.h"
+#include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/ToolOutputFile.h"
+
+using namespace llvm;
+
+static cl::opt<bool>
+    BinaryExtract("b", cl::desc("Whether to perform binary extraction"));
+
+static cl::opt<std::string> OutputFilename("o", cl::Required,
+                                           cl::desc("Output filename"),
+                                           cl::value_desc("filename"));
+
+static cl::opt<std::string>
+    InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
+
+static cl::opt<unsigned> ModuleIndex("n", cl::Required,
+                                     cl::desc("Index of module to extract"),
+                                     cl::value_desc("index"));
+
+int main(int argc, char **argv) {
+  cl::ParseCommandLineOptions(argc, argv, "Module extractor");
+
+  ExitOnError ExitOnErr("llvm-modextract: error: ");
+
+  std::unique_ptr<MemoryBuffer> MB =
+      ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
+  std::vector<BitcodeModule> Ms = ExitOnErr(getBitcodeModuleList(*MB));
+
+  LLVMContext Context;
+  if (ModuleIndex >= Ms.size()) {
+    errs() << "llvm-modextract: error: module index out of range; bitcode file "
+              "contains "
+           << Ms.size() << " module(s)\n";
+    return 1;
+  }
+
+  std::error_code EC;
+  std::unique_ptr<tool_output_file> Out(
+      new tool_output_file(OutputFilename, EC, sys::fs::F_None));
+  ExitOnErr(errorCodeToError(EC));
+
+  if (BinaryExtract) {
+    SmallVector<char, 0> Header;
+    BitcodeWriter Writer(Header);
+    Out->os() << Header << Ms[ModuleIndex].getBuffer();
+    return 0;
+  }
+
+  std::unique_ptr<Module> M = ExitOnErr(Ms[ModuleIndex].parseModule(Context));
+  WriteBitcodeToFile(M.get(), Out->os());
+
+  return 0;
+}