Index: llvm/docs/Phabricator.rst
===================================================================
--- llvm/docs/Phabricator.rst
+++ llvm/docs/Phabricator.rst
@@ -62,6 +62,33 @@
 * ``git format-patch -U999999 @{u}``
 * ``svn diff --diff-cmd=diff -x -U999999``
 
+Additionally, before sending a patch for review, please also try to ensure it's
+formatted properly. We use ``clang-format`` for this, which has git integration
+through the ``git-clang-format`` script. On some systems, it may already be
+installed (or be installable via your package manager). If so, you can simply
+run it -- the following command will format only the code changed in the most
+recent commit:
+
+.. code-block:: console
+
+  % git clang-format HEAD~1
+
+Note that this modifies the files, but doesn't commit them -- you'll likely want
+to run
+
+.. code-block:: console
+
+  % git commit --amend -a
+
+in order to update the last commit with all pending changes.
+
+.. note::
+  If you don't already have ``clang-format`` or ``git clang-format`` installed
+  on your system, the ``clang-format`` binary will be built alongside clang, and
+  the git integration can be run from
+  ``clang/tools/clang-format/git-clang-format``.
+
+
 To upload a new patch:
 
 * Click *Differential*.