diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index a06be9dfb9403..3ba94d0d483bf 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -3388,6 +3388,10 @@ the object's lifetime. A stack object's lifetime can be explicitly specified
 using :ref:`llvm.lifetime.start <int_lifestart>` and
 :ref:`llvm.lifetime.end <int_lifeend>` intrinsic function calls.
 
+As an exception to the above, loading from a stack object outside its lifetime
+is not undefined behavior and returns a poison value instead. Storing to it is
+still undefined behavior.
+
 .. _pointeraliasing:
 
 Pointer Aliasing Rules