Index: llvm/docs/BitCodeFormat.rst
===================================================================
--- llvm/docs/BitCodeFormat.rst
+++ llvm/docs/BitCodeFormat.rst
@@ -1058,7 +1058,16 @@
 * code 56: ``nocf_check``
 * code 57: ``optforfuzzing``
 * code 58: ``shadowcallstack``
+* code 59: ``speculative_load_hardening``
+* code 60: ``immarg``
+* code 61: ``willreturn``
+* code 62: ``nofree``
+* code 63: ``nosync``
 * code 64: ``sanitize_memtag``
+* code 65: ``preallocated``
+* code 66: ``no_merge``
+* code 67: ``null_pointer_is_valid``
+* code 68: ``noundef``
 
 .. note::
   The ``allocsize`` attribute has a special encoding for its arguments. Its two
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1252,6 +1252,12 @@
     only valid on intrinsic declarations and cannot be applied to a
     call site or arbitrary function.
 
+``noundef``
+    This attribute applies to parameters and return values. If the value contains
+    any uninitialized or poison bits, the behavior is undefined. This constraint does
+    not apply to inferrable uninitialized bits, such as the 24 bits of
+    padding in `{ i8, i32 }`.
+
 .. _gc:
 
 Garbage Collector Strategy Names
@@ -3656,6 +3662,11 @@
 -  The condition operand of a :ref:`br <i_br>` instruction.
 -  The callee operand of a :ref:`call <i_call>` or :ref:`invoke <i_invoke>`
    instruction.
+-  The parameter operand of a :ref:`call <i_call>` or :ref:`invoke <i_invoke>`
+   instruction, when the function or invoking call site has a ``noundef``
+   attribute in the corresponding position.
+-  The operand of a :ref:`ret <i_ret>` instruction if the function or invoking
+   call site has a `noundef` attribute in the return value position.
 
 Here are some examples: