Index: docs/CodingStandards.rst
===================================================================
--- docs/CodingStandards.rst
+++ docs/CodingStandards.rst
@@ -494,8 +494,8 @@
 This is one of many contentious issues in coding standards, but it is not up for
 debate.
 
-Use Spaces Instead of Tabs
-^^^^^^^^^^^^^^^^^^^^^^^^^^
+Whitespace
+^^^^^^^^^^
 
 In all cases, prefer spaces to tabs in source files.  People have different
 preferred indentation levels, and different styles of indentation that they
@@ -509,6 +509,12 @@
 of indentation.  Also, do not reindent a whole source file: it makes for
 incredible diffs that are absolutely worthless.
 
+Do not commit changes that include trailing whitespace. If you find trailing
+whitespace in a file, do not remove it unless you're otherwise changing that
+line of code. Some common editors will automatically remove trailing whitespace
+when saving a file which causes unrelated changes to appear in diffs and
+commits.
+
 Indent Code Consistently
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
Index: docs/DeveloperPolicy.rst
===================================================================
--- docs/DeveloperPolicy.rst
+++ docs/DeveloperPolicy.rst
@@ -376,7 +376,13 @@
    obvious. This is clearly a subjective decision --- we simply expect you to
    use good judgement.  Examples include: fixing build breakage, reverting
    obviously broken patches, documentation/comment changes, any other minor
-   changes.
+   changes. Avoid committing formatting- or whitespace-only changes outside of
+   code you plan to make subsequent changes to. Also, try to separate
+   formatting or whitespace changes from functional changes, either by
+   correcting the format first (ideally) or afterward. Such changes should be
+   highly localized and the commit message should clearly state that the commit
+   is not intended to change functionality, usually by stating it is
+   :ref:`NFC <nfc>`.
 
 #. You are allowed to commit patches without approval to those portions of LLVM
    that you have contributed or maintain (i.e., have been assigned
Index: docs/Lexicon.rst
===================================================================
--- docs/Lexicon.rst
+++ docs/Lexicon.rst
@@ -185,6 +185,7 @@
 
 N
 -
+.. _nfc:
 
 **NFC**
   "No functional change". Used in a commit message to indicate that a patch