diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -499,6 +499,15 @@
   (e.g. ``int : 0``) no longer prevents the structure from being considered a
   homogeneous floating-point or vector aggregate. The new behavior agrees with
   the AAPCS specification, and matches the similar bug fix in GCC 12.1.
+- Targeting AArch64, LLVM now only preserves the z8-z23 registers across
+  a call if the registers z0-z7 are used to pass data into or out of a
+  subroutine. This new behavior now matches the AAPCS. Previously LLVM
+  preserved z8-z23 across a call if the callee had an SVE type anywhere
+  in its signature. This would cause an incorrect use of the
+  caller-preserved z8-z23 ABI for example if the 9th argument to a
+  function were an SVE type. The analogous issue and fix applies to
+  predicate register arguments (p0-p3 for passing between subroutines,
+  and p4-15 preserved).
 - All copy constructors can now be trivial if they are not user-provided,
   regardless of the type qualifiers of the argument of the defaulted constructor,
   fixing dr2171.