diff --git a/clang-tools-extra/include-fixer/IncludeFixer.h b/clang-tools-extra/include-fixer/IncludeFixer.h
@@ -0,0 +1,46 @@
+//===-- IncludeFixer.h - Include inserter -----------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_INCLUDEFIXER_H
+#define LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_INCLUDEFIXER_H
+
+#include "XrefsDB.h"
+#include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Tooling/Core/Replacement.h"
+#include "clang/Tooling/Tooling.h"
+
+namespace clang {
+namespace include_fixer {
+
+class IncludeFixerActionFactory : public clang::tooling::ToolAction {
+public:
+  /// \param Xrefs A source for matching symbols to header files.
+  /// \param Replacements Storage for the output of the fixer.
+  IncludeFixerActionFactory(
+      XrefsDB &Xrefs, std::vector<clang::tooling::Replacement> &Replacements);
+  ~IncludeFixerActionFactory();
+
+  bool
+  runInvocation(clang::CompilerInvocation *Invocation,
+                clang::FileManager *Files,
+                std::shared_ptr<clang::PCHContainerOperations> PCHContainerOps,
+                clang::DiagnosticConsumer *Diagnostics) override;
+
+private:
+  /// The client to use to find cross-references.
+  XrefsDB &Xrefs;
+
+  /// Replacements are written here.
+  std::vector<clang::tooling::Replacement> &Replacements;
+};
+
+} // namespace include_fixer
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_INCLUDEFIXER_H
diff --git a/clang-tools-extra/include-fixer/XrefsDB.h b/clang-tools-extra/include-fixer/XrefsDB.h
@@ -0,0 +1,38 @@
+//===-- XrefsDB.h - Interface for symbol-header matching --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_XREFSDB_H
+#define LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_XREFSDB_H
+
+#include "llvm/ADT/StringRef.h"
+#include <vector>
+
+namespace clang {
+namespace include_fixer {
+
+/// This class provides an interface for finding the header files corresponding
+/// to an indentifier in the source code.
+class XrefsDB {
+public:
+  virtual ~XrefsDB() = default;
+
+  /// Search for header files to be included for an identifier.
+  /// \param Identifier The identifier being searched for. May or may not be
+  ///                   fully qualified.
+  /// \returns A list of inclusion candidates, in a format ready for being
+  ///          pasted after an #include token.
+  // FIXME: Expose the type name so we can also insert using declarations (or
+  // fix the usage)
+  virtual std::vector<std::string> search(llvm::StringRef Identifier) = 0;
+};
+
+} // namespace include_fixer
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_INCLUDE_FIXER_XREFSDB_H
diff --git a/clang-tools-extra/include-fixer/tool/CMakeLists.txt b/clang-tools-extra/include-fixer/tool/CMakeLists.txt
@@ -0,0 +1,11 @@
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/..)
+
+add_clang_executable(clang-include-fixer ClangIncludeFixer.cpp)
+target_link_libraries(clang-include-fixer
+  clangBasic
+  clangFrontend
+  clangIncludeFixer
+  clangRewrite
+  clangTooling
+  clangToolingCore
+  )
diff --git a/clang-tools-extra/include-fixer/tool/ClangIncludeFixer.cpp b/clang-tools-extra/include-fixer/tool/ClangIncludeFixer.cpp
@@ -0,0 +1,50 @@
+//===-- ClangIncludeFixer.cpp - Standalone include fixer ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InMemoryXrefsDB.h"
+#include "IncludeFixer.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
+#include "clang/Rewrite/Core/Rewriter.h"
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/Support/CommandLine.h"
+using namespace clang;
+
+static llvm::cl::OptionCategory tool_options("Tool options");
+
+int main(int argc, char **argv) {
+  clang::tooling::CommonOptionsParser options(argc, (const char **)argv,
+                                              tool_options);
+  clang::tooling::ClangTool tool(options.getCompilations(),
+                                 options.getSourcePathList());
+  // Set up the data source.
+  std::map<std::string, std::vector<std::string>> XrefsMap = {
+      {"std::string", {"<string>"}}};
+  auto XrefsDB =
+      llvm::make_unique<include_fixer::InMemoryXrefsDB>(std::move(XrefsMap));
+
+  // Now run our tool.
+  std::vector<clang::tooling::Replacement> Replacements;
+  include_fixer::IncludeFixerActionFactory Factory(*XrefsDB, Replacements);
+
+  tool.run(&Factory); // Always succeeds.
+
+  // Set up a new source manager for applying the resulting replacements.
+  llvm::IntrusiveRefCntPtr<clang::DiagnosticOptions> DiagOpts(
+      new clang::DiagnosticOptions);
+  clang::DiagnosticsEngine Diagnostics(new clang::DiagnosticIDs, &*DiagOpts);
+  clang::TextDiagnosticPrinter DiagnosticPrinter(llvm::outs(), &*DiagOpts);
+  clang::SourceManager source_manager(Diagnostics, tool.getFiles());
+  Diagnostics.setClient(&DiagnosticPrinter, false);
+
+  // Write replacements to disk.
+  clang::Rewriter Rewrites(source_manager, clang::LangOptions());
+  clang::tooling::applyAllReplacements(Replacements, Rewrites);
+  return Rewrites.overwriteChangedFiles();
+}
diff --git a/clang-tools-extra/unittests/CMakeLists.txt b/clang-tools-extra/unittests/CMakeLists.txt
@@ -9,3 +9,4 @@ add_subdirectory(clang-apply-replacements)
 add_subdirectory(clang-rename)
 add_subdirectory(clang-query)
 add_subdirectory(clang-tidy)
+add_subdirectory(include-fixer)
diff --git a/clang-tools-extra/unittests/include-fixer/CMakeLists.txt b/clang-tools-extra/unittests/include-fixer/CMakeLists.txt
@@ -0,0 +1,22 @@
+set(LLVM_LINK_COMPONENTS
+  support
+  )
+
+get_filename_component(INCLUDE_FIXER_SOURCE_DIR
+  ${CMAKE_CURRENT_SOURCE_DIR}/../../include-fixer REALPATH)
+include_directories(
+  ${INCLUDE_FIXER_SOURCE_DIR}
+  )
+
+add_extra_unittest(IncludeFixerTests
+  IncludeFixerTest.cpp
+  )
+
+target_link_libraries(IncludeFixerTests
+  clangBasic
+  clangFrontend
+  clangIncludeFixer
+  clangRewrite
+  clangTooling
+  clangToolingCore
+  )
diff --git a/clang-tools-extra/unittests/include-fixer/IncludeFixerTest.cpp b/clang-tools-extra/unittests/include-fixer/IncludeFixerTest.cpp
@@ -0,0 +1,87 @@
+//===-- IncludeFixerTest.cpp - Include fixer unit tests -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../../../../unittests/Tooling/RewriterTestContext.h"
+#include "InMemoryXrefsDB.h"
+#include "IncludeFixer.h"
+#include "clang/Tooling/Tooling.h"
+#include "gtest/gtest.h"
+using namespace clang;
+
+namespace clang {
+namespace include_fixer {
+namespace {
+
+static bool runOnCode(tooling::ToolAction *ToolAction, StringRef Code,
+                      StringRef FileName) {
+  llvm::IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
+      new vfs::InMemoryFileSystem);
+  llvm::IntrusiveRefCntPtr<FileManager> Files(
+      new FileManager(FileSystemOptions(), InMemoryFileSystem));
+  tooling::ToolInvocation Invocation(
+      {std::string("include_fixer"), std::string("-fsyntax-only"),
+       FileName.str()},
+      ToolAction, Files.get(), std::make_shared<PCHContainerOperations>());
+
+  InMemoryFileSystem->addFile(FileName, 0,
+                              llvm::MemoryBuffer::getMemBuffer(Code));
+
+  InMemoryFileSystem->addFile("foo.h", 0,
+                              llvm::MemoryBuffer::getMemBuffer("\n"));
+  InMemoryFileSystem->addFile("bar.h", 0,
+                              llvm::MemoryBuffer::getMemBuffer("\n"));
+  return Invocation.run();
+}
+
+static std::string runIncludeFixer(StringRef Code) {
+  std::map<std::string, std::vector<std::string>> XrefsMap = {
+      {"std::string", {"<string>"}}, {"std::string::size_type", {"<string>"}}};
+  auto XrefsDB =
+      llvm::make_unique<include_fixer::InMemoryXrefsDB>(std::move(XrefsMap));
+  std::vector<clang::tooling::Replacement> Replacements;
+  IncludeFixerActionFactory Factory(*XrefsDB, Replacements);
+  runOnCode(&Factory, Code, "input.cc");
+  clang::RewriterTestContext Context;
+  clang::FileID ID = Context.createInMemoryFile("input.cc", Code);
+  clang::tooling::applyAllReplacements(Replacements, Context.Rewrite);
+  return Context.getRewrittenText(ID);
+}
+
+TEST(IncludeFixer, Typo) {
+  EXPECT_EQ("#include <string>\nstd::string foo;\n",
+            runIncludeFixer("std::string foo;\n"));
+
+  EXPECT_EQ(
+      "// comment\n#include <string>\n#include \"foo.h\"\nstd::string foo;\n"
+      "#include \"bar.h\"\n",
+      runIncludeFixer("// comment\n#include \"foo.h\"\nstd::string foo;\n"
+                      "#include \"bar.h\"\n"));
+
+  EXPECT_EQ("#include <string>\n#include \"foo.h\"\nstd::string foo;\n",
+            runIncludeFixer("#include \"foo.h\"\nstd::string foo;\n"));
+
+  EXPECT_EQ(
+      "#include <string>\n#include \"foo.h\"\nstd::string::size_type foo;\n",
+      runIncludeFixer("#include \"foo.h\"\nstd::string::size_type foo;\n"));
+
+  // The fixed xrefs db doesn't know how to handle string without std::.
+  EXPECT_EQ("string foo;\n", runIncludeFixer("string foo;\n"));
+}
+
+TEST(IncludeFixer, IncompleteType) {
+  EXPECT_EQ(
+      "#include <string>\n#include \"foo.h\"\n"
+      "namespace std {\nclass string;\n}\nstring foo;\n",
+      runIncludeFixer("#include \"foo.h\"\n"
+                      "namespace std {\nclass string;\n}\nstring foo;\n"));
+}
+
+} // namespace
+} // namespace include_fixer
+} // namespace clang