diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -2052,7 +2052,8 @@
     This attribute sets a threshold to emit diagnostics once the frame size is
     known should the frame size exceed the specified value.  It takes one
     required integer value, which should be a non-negative integer, and less
-    than `UINT_MAX`.
+    than `UINT_MAX`.  It's unspecified which threshold will be used when
+    duplicate definitions are linked together with differing values.
 ``vscale_range(<min>[, <max>])``
     This attribute indicates the minimum and maximum vscale value for the given
     function. A value of 0 means unbounded. If the optional max value is omitted