diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 293144a832700f25b0e043b62fc1c4c0e9e3d84d..698672e479099aae4a1f5e2983c8d8e7a80a3a4b 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -103,6 +103,13 @@ New Compiler Flags
 
 - --autocomplete was implemented to obtain a list of flags and its arguments. This is used for shell autocompletion.
 
+- The ``-fdouble-square-bracket-attributes`` and corresponding
+  ``-fno-double-square-bracket-attributes`` flags were added to enable or
+  disable [[]] attributes in any language mode. Currently, only a limited
+  number of attributes are supported outside of C++ mode. See the Clang
+  attribute documentation for more information about which attributes are
+  supported for each syntax.
+
 Deprecated Compiler Flags
 -------------------------