diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1953,6 +1953,12 @@
     the function. The instrumentation checks that the return address for the
     function has not changed between the function prolog and epilog. It is
     currently x86_64-specific.
+``maynotprogress``
+    This attribute indicates that the function is permitted to not make
+    progress, however this does not apply transitively to its callees.
+    Progress is defined as per the `C++ Standard <http://eel.is/c++draft/intro.progress>`_.
+    Functions without this attribute are implicitly ``mustprogress`` and
+    they are required to make progress.
 
 Call Site Attributes
 ----------------------