diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1234,7 +1234,8 @@
     size of the pointee type. The ``nonnull`` attribute does not imply
     dereferenceability (consider a pointer to one element past the end of an
     array), however ``dereferenceable(<n>)`` does imply ``nonnull`` in
-    ``addrspace(0)`` (which is the default address space).
+    ``addrspace(0)`` (which is the default address space), except if the
+    ``null_pointer_is_valid`` function attribute is present.
 
 ``dereferenceable_or_null(<n>)``
     This indicates that the parameter or return value isn't both