Index: docs/include-fixer.rst
===================================================================
--- docs/include-fixer.rst
+++ docs/include-fixer.rst
@@ -51,6 +51,20 @@
   $ clang-include-fixer -db=yaml path/to/file/with/missing/include.cpp
     Added #include "foo.h"
 
+Integrate with Vim
+-------------------
+To run `clang-include-fixer` on a potentially unsaved buffer in Vim. Add the
+following key binding to your ``.vimrc``:
+
+.. code-block:: console
+
+  map ,cf :pyf path/to/llvm/source/tools/clang/tools/extra/include-fixer/tool/clang-include-fixer.py<cr>
+
+This enables `clang-include-fixer` for NORMAL and VISUAL mode. Change ``,cf`` to
+another binding if you need clang-include-fixer on a different key.
+
+See ``clang-include-fixer.py`` for more details.
+
 How it Works
 ============
 
Index: include-fixer/tool/ClangIncludeFixer.cpp
===================================================================
--- include-fixer/tool/ClangIncludeFixer.cpp
+++ include-fixer/tool/ClangIncludeFixer.cpp
@@ -47,11 +47,40 @@
 cl::opt<bool> Quiet("q", cl::desc("Reduce terminal output"), cl::init(false),
                     cl::cat(IncludeFixerCategory));
 
+cl::opt<bool>
+    STDINMode("stdin",
+              cl::desc("Override source file's content (in the overlaying\n"
+                       "virtual file system) with input from <stdin> and run\n"
+                       "the tool on the new content with the compilation\n"
+                       "options of the source file. This mode is currently\n"
+                       "used for editor integration."),
+              cl::init(false), cl::cat(IncludeFixerCategory));
+
 int includeFixerMain(int argc, const char **argv) {
   tooling::CommonOptionsParser options(argc, argv, IncludeFixerCategory);
   tooling::ClangTool tool(options.getCompilations(),
                           options.getSourcePathList());
 
+  // In STDINMode, we override the file content with the <stdin> input.
+  // Since `tool.mapVirtualFile` takes `StringRef`, we define `Code` outside of
+  // the if-block so that `Code` is not released after the if-block.
+  std::unique_ptr<llvm::MemoryBuffer> Code;
+  if (STDINMode) {
+    assert(options.getSourcePathList().size() == 1 &&
+           "Expect exactly one file path in STDINMode.");
+    llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> CodeOrErr =
+        MemoryBuffer::getSTDIN();
+    if (std::error_code EC = CodeOrErr.getError()) {
+      errs() << EC.message() << "\n";
+      return 1;
+    }
+    Code = std::move(CodeOrErr.get());
+    if (Code->getBufferSize() == 0)
+      return 0;  // Skip empty files.
+
+    tool.mapVirtualFile(options.getSourcePathList().front(), Code->getBuffer());
+  }
+
   // Set up data source.
   auto SymbolIndexMgr = llvm::make_unique<include_fixer::SymbolIndexManager>();
   switch (DatabaseFormat) {
@@ -121,6 +150,15 @@
   SourceManager SM(Diagnostics, tool.getFiles());
   Diagnostics.setClient(&DiagnosticPrinter, false);
 
+  if (STDINMode) {
+    for (const tooling::Replacement &Replacement : Replacements) {
+      FileID ID = SM.getMainFileID();
+      unsigned LineNum = SM.getLineNumber(ID, Replacement.getOffset());
+      llvm::outs() << LineNum << "," << Replacement.getReplacementText();
+    }
+    return 0;
+  }
+
   // Write replacements to disk.
   Rewriter Rewrites(SM, LangOptions());
   tooling::applyAllReplacements(Replacements, Rewrites);
Index: include-fixer/tool/clang-include-fixer.py
===================================================================
--- /dev/null
+++ include-fixer/tool/clang-include-fixer.py
@@ -0,0 +1,65 @@
+# This file is a minimal clang-include-fixer vim-integration. To install:
+# - Change 'binary' if clang-include-fixer is not on the path (see below).
+# - Add to your .vimrc:
+#
+#   map ,cf :pyf path/to/llvm/source/tools/clang/tools/extra/include-fixer/tool/clang-include-fixer.py<cr>
+#
+# This enables clang-include-fixer for NORMAL and VISUAL mode. Change ",cf" to
+# another binding if you need clang-include-fixer on a different key.
+#
+# To set up clang-include-fixer, see http://clang.llvm.org/extra/include-fixer.html
+#
+# With this integration you can press the bound key and clang-include-fixer will
+# be run on the current buffer.
+#
+# It operates on the current, potentially unsaved buffer and does not create
+# or save any files. To revert a fix, just undo.
+
+import argparse
+import subprocess
+import sys
+import vim
+
+# set g:clang_include_fixer_path to the path to clang-include-fixer if it is not
+# on the path.
+# Change this to the full path if clang-include-fixer is not on the path.
+binary = 'clang-include-fixer'
+if vim.eval('exists("g:clang_include_fixer_path")') == "1":
+  binary = vim.eval('g:clang_include_fixer_path')
+
+def main():
+  parser = argparse.ArgumentParser(
+      description='Vim integration for clang-include-fixer')
+  parser.add_argument('-db', default='yaml',
+                      help='clang-include-fixer input format.')
+  parser.add_argument('-input', default='',
+                      help='String to initialize the database.')
+  args = parser.parse_args()
+
+  # Get the current text.
+  buf = vim.current.buffer
+  text = '\n'.join(buf)
+
+  # Call clang-include-fixer.
+  command = [binary, "-stdin", "-db="+args.db, "-input="+args.input,
+             vim.current.buffer.name]
+  p = subprocess.Popen(command,
+                       stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                       stdin=subprocess.PIPE)
+  stdout, stderr = p.communicate(input=text)
+
+  # If successful, replace buffer contents.
+  if stderr:
+    print stderr
+
+  if stdout:
+    lines = stdout.splitlines()
+    for line in lines:
+      line_num, text = line.split(",")
+      # clang-include-fixer provides 1-based line number
+      line_num = int(line_num) - 1
+      print 'Inserting "{0}" at line {1}'.format(text, line_num)
+      vim.current.buffer[line_num:line_num] = [text]
+
+if __name__ == '__main__':
+  main()