diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -4303,9 +4303,20 @@
 
     call void asm inteldialect "eieio", ""()
 
-If multiple keywords appear the '``sideeffect``' keyword must come
-first, the '``alignstack``' keyword second and the '``inteldialect``'
-keyword last.
+In the case that the inline asm might unwind the stack,
+the '``unwind``' keyword must be used, so that the compiler emits
+unwinding information:
+
+.. code-block:: llvm
+
+    call void asm unwind "call func", ""()
+
+If the inline asm unwinds the stack and isn't marked with
+the '``unwind``' keyword, the behavior is undefined.
+
+If multiple keywords appear, the '``sideeffect``' keyword must come
+first, the '``alignstack``' keyword second, the '``inteldialect``' keyword
+third and the '``unwind``' keyword last.
 
 Inline Asm Constraint String
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^