Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -51,6 +51,9 @@
   linkers that is a relatively expensive option. It can be passed explicitly
   with -Wl,--build-id. To have clang always pass it, build clang with
   -DENABLE_LINKER_BUILD_ID.
+- On Itanium ABI targets, attribute abi_tag is now supported for compatibility
+  with GCC. Clang implementation of abi_tag is mostly compatible with GCC ABI
+  version 10.
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^