diff --git a/clang/lib/Tooling/CommonOptionsParser.cpp b/clang/lib/Tooling/CommonOptionsParser.cpp
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+++ b/clang/lib/Tooling/CommonOptionsParser.cpp
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+//===--- CommonOptionsParser.cpp - common options for clang tools ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements the CommonOptionsParser class used to parse common
+//  command-line options for clang tools, so that they can be run as separate
+//  command-line applications with a consistent common interface for handling
+//  compilation database and input files.
+//
+//  It provides a common subset of command-line options, common algorithm
+//  for locating a compilation database and source files, and help messages
+//  for the basic command-line interface.
+//
+//  It creates a CompilationDatabase and reads common command-line options.
+//
+//  This class uses the Clang Tooling infrastructure, see
+//    http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html
+//  for details on setting it up with LLVM source tree.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CommandLine.h"
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "clang/Tooling/Tooling.h"
+
+using namespace clang::tooling;
+using namespace llvm;
+
+const char *const clang::tooling::CommonHelpMessage =
+    "\n"
+    "-p <build-path> is used to read a compile command database.\n"
+    "\n"
+    "\tFor example, it can be a CMake build directory in which a file named\n"
+    "\tcompile_commands.json exists (use -DCMAKE_EXPORT_COMPILE_COMMANDS=ON\n"
+    "\tCMake option to get this output). When no build path is specified,\n"
+    "\tclang-check will attempt to locate it automatically using all parent\n"
+    "\tpaths of the first input file. See:\n"
+    "\thttp://clang.llvm.org/docs/HowToSetupToolingForLLVM.html for an\n"
+    "\texample of setting up Clang Tooling on a source tree.\n"
+    "\n"
+    "<source0> ... specify the paths of source files. These paths are\n"
+    "\tlooked up in the compile command database. If the path of a file is\n"
+    "\tabsolute, it needs to point into CMake's source tree. If the path is\n"
+    "\trelative, the current working directory needs to be in the CMake\n"
+    "\tsource tree and the file must be in a subdirectory of the current\n"
+    "\tworking directory. \"./\" prefixes in the relative files will be\n"
+    "\tautomatically removed, but the rest of a relative path must be a\n"
+    "\tsuffix of a path in the compile command database.\n"
+    "\n";
+
+static cl::opt<std::string> BuildPath(
+    "p", cl::desc("Build path"), cl::Optional);
+
+static cl::list<std::string> SourcePaths(
+    cl::Positional, cl::desc("<source0> [... <sourceN>]"), cl::OneOrMore);
+
+CommonOptionsParser::CommonOptionsParser(int &argc, const char **argv) {
+  Compilations.reset(FixedCompilationDatabase::loadFromCommandLine(argc,
+                                                                   argv));
+  cl::ParseCommandLineOptions(argc, argv);
+  SourcePathList = SourcePaths;
+  if (!Compilations) {
+    std::string ErrorMessage;
+    if (!BuildPath.empty()) {
+      Compilations.reset(CompilationDatabase::autoDetectFromDirectory(
+                              BuildPath, ErrorMessage));
+    } else {
+      Compilations.reset(CompilationDatabase::autoDetectFromSource(
+                              SourcePaths[0], ErrorMessage));
+    }
+    if (!Compilations)
+      llvm::report_fatal_error(ErrorMessage);
+  }
+}