diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -24568,6 +24568,9 @@
 intrinsic, with the added constraint that ``len`` is required to be a positive integer
 multiple of the ``element_size``. If ``len`` is not a positive integer multiple of
 ``element_size``, then the behaviour of the intrinsic is undefined.
+If compiled for garbage collected environment which requires load/store barriers,
+``dest`` and ``src`` arguments should have ``elementtype`` attribute set. It
+must specify type of elements being copied.
 
 ``element_size`` must be a compile-time constant positive power of two no greater than
 target-specific atomic access size limit.
@@ -24644,6 +24647,9 @@
 ``len`` is required to be a positive integer multiple of the ``element_size``.
 If ``len`` is not a positive integer multiple of ``element_size``, then the
 behaviour of the intrinsic is undefined.
+If compiled for garbage collected environment which requires load/store barriers,
+``dest`` and ``src`` arguments should have ``elementtype`` attribute set. It
+must specify type of elements being moved.
 
 ``element_size`` must be a compile-time constant positive power of two no
 greater than a target-specific atomic access size limit.