diff --git a/llvm/docs/Phabricator.rst b/llvm/docs/Phabricator.rst
index 6fdea1f94172..c428f416bff1 100644
--- a/llvm/docs/Phabricator.rst
+++ b/llvm/docs/Phabricator.rst
@@ -94,6 +94,26 @@ when a review changes state, for example by clicking "Accept Revision" in
 the web interface. Thus, please type LGTM into the comment box to accept
 a change from Phabricator.
 
+Committing a change
+-------------------
+
+When committing an LLVM change that has been reviewed using
+Phabricator, the convention is for the commit message to end with the
+line:
+
+::
+
+  Differential Revision: <URL>
+
+where ``<URL>`` is the URL for the code review, starting with
+``http://llvm-reviews.chandlerc.com/``.
+
+Note that Arcanist will add this automatically.
+
+This allows people reading the version history to see the review for
+context.  This also allows Phabricator to detect the commit, close the
+review, and add a link from the review to the commit.
+
 Status
 ------