diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -2240,8 +2240,8 @@
 
 Clang supports the
 ``__attribute__((amdgpu_flat_work_group_size(<min>, <max>)))`` attribute for the
-AMDGPU target. This attribute may be attached to a kernel function definition
-and is an optimization hint.
+AMDGPU target. This attribute can be attached to a kernel function definition
+and is mandatory in some situations.
 
 ``<min>`` parameter specifies the minimum flat work-group size, and ``<max>``
 parameter specifies the maximum flat work-group size (must be greater than