diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -51,7 +51,7 @@
   restores the former behavior. The ``-v`` and ``-###`` flags will print
   "(in-process)" when compilations are done in-process.
 
-- ...
+- Concepts support. Clang now supports C++2a Concepts under the -std=c++2a flag.
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -123,6 +123,10 @@
   You can also force vzeroupper insertion to be used on CPUs that normally
   wouldn't with -mvzeroupper.
 
+- The -fno-concept-satisfaction-caching can be used to disable caching for
+  satisfactions of Concepts. Using this flag might incur significant
+  compile-time costs.
+
 Deprecated Compiler Flags
 -------------------------
 
@@ -132,6 +136,8 @@
 - -mmpx used to enable the __MPX__ preprocessor define for the Intel MPX
   instructions. There were no MPX intrinsics.
 - -mno-mpx used to disable -mmpx and is the default behavior.
+- -fconcepts-ts previously used to enable experimental concepts support. Use
+  -std=c++2a instead to enable Concepts support.
 
 - ...