Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -88,6 +88,14 @@
   ``llvm/Config/llvm-config.h``.  If you used this macro, use the compiler-set
   ``_WIN32`` instead which is set exactly when ``LLVM_ON_WIN32`` used to be set.
 
+* The ``DEBUG`` macro has been renamed to ``LLVM_DEBUG``. The interface remains
+  the same.  If you used this macro you need to migrate to the new one, you can
+  do this with the following bash command:
+
+.. code-block:: bash
+
+    git grep -l 'DEBUG' | xargs perl -pi -e 's/\bDEBUG\s?\(/LLVM_DEBUG(/g'
+
 * Note..
 
 .. NOTE