diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index d1075da16a9..5cd2386c920 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -101,6 +101,11 @@ During this release ...
 * The assembler now has support for {disp32} and {disp8} pseudo prefixes for
   controlling displacement size for memory operands and jump displacements. The
   assembler also supports the .d32 and .d8 mnemonic suffixes to do the same.
+* A new function attribute "tune-cpu" has been added to support -mtune like gcc.
+  This allows microarchitectural optimizations to be applied independent from
+  the "target-cpu" attribute or TargetMachine CPU which will be used to select
+  Instruction Set. If the attribute is not present, the tune CPU will follow
+  the target CPU.
 
 Changes to the AMDGPU Target
 -----------------------------