diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 06cc31f8c5c97..739fd50179d25 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -211,6 +211,7 @@ Deprecated Compiler Flags
 
 Modified Compiler Flags
 -----------------------
+- The `-gkey-instructions` compiler flag is now enabled by default when DWARF is emitted for plain C/C++ and optimizations are enabled. (#GH149509)
 
 Removed Compiler Flags
 -------------------------