diff --git a/clang/docs/ClangFormat.rst b/clang/docs/ClangFormat.rst
--- a/clang/docs/ClangFormat.rst
+++ b/clang/docs/ClangFormat.rst
@@ -82,8 +82,10 @@
 
 When the desired code formatting style is different from the available options,
 the style can be customized using the ``-style="{key: value, ...}"`` option or
-by putting your style configuration in the ``.clang-format`` or ``_clang-format``
-file in your project's directory and using ``clang-format -style=file``.
+by putting your style configuration a file named ``.{ext}.clang-format`` (``{ext}``
+is the file name extension, e.g. ``.cpp.clang-format`` is the formatted file
+is named ``something.cpp``), ``.clang-format`` or ``_clang-format`` in your
+project's directory and using ``clang-format -style=file``.
 
 An easy way to create the ``.clang-format`` file is:
 
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -2601,6 +2601,11 @@
     return make_string_error(EC.message());
 
   llvm::SmallVector<std::string, 2> FilesToLookFor;
+
+  auto Extension(llvm::sys::path::extension(FileName));
+  if (Extension != "") {
+    FilesToLookFor.push_back((Extension + ".clang-format").str());
+  }
   FilesToLookFor.push_back(".clang-format");
   FilesToLookFor.push_back("_clang-format");