Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -138,6 +138,12 @@
   please let us know if you encounter a situation where you need to specify this
   flag for correct program behavior.
 
+- ``-fmacro-prefix-map=OLD=NEW`` substitutes directory prefix ``OLD`` for
+  ``NEW`` in predefined preprocessor macros such as ``__FILE__``. This helps
+  with reproducible builds that are location independent. The new
+  ``-ffile-prefix-map`` option is equivalent to specifying both
+  ``-fdebug-prefix-map`` and ``-fmacro-prefix-map``.
+
 Deprecated Compiler Flags
 -------------------------