Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -16924,14 +16924,15 @@
 
 ::
 
-      %m[i] = icmp ule (%base + i), %n
+      %m[i] = icmp ule (%base + i), %n - 1
 
 where ``%m`` is a vector (mask) of active/inactive lanes with its elements
 indexed by ``i``,  and ``%base``, ``%n`` are the two arguments to
 ``llvm.get.active.lane.mask.*``, ``%imcp`` is an integer compare and ``ule``
 the unsigned less-than-equal comparison operator.  Overflow cannot occur in
-``(%base + i)`` and its comparison against ``%n`` as it is performed in integer
-numbers and not in machine numbers.  The above is equivalent to:
+``(%base + i)`` and its comparison against ``%n`` with ``%n > 0``, as it is
+performed in integer numbers and not in machine numbers. The above is
+equivalent to:
 
 ::
 
@@ -16939,13 +16940,13 @@
 
 This can, for example, be emitted by the loop vectorizer. Then, ``%base`` is
 the first element of the vector induction variable (VIV), and ``%n`` is the
-Back-edge Taken Count (BTC). Thus, these intrinsics perform an element-wise
-less than or equal comparison of VIV with BTC, producing a mask of true/false
-values representing active/inactive vector lanes, except if the VIV overflows
-in which case they return false in the lanes where the VIV overflows.  The
-arguments are scalar types to accommodate scalable vector types, for which it is
-unknown what the type of the step vector needs to be that enumerate its
-lanes without overflow.
+loop tripcount. Since ``%n - 1`` corresponds to the Back-edge Taken Count
+(BTC), these intrinsics perform an element-wise less than or equal comparison
+of VIV with BTC, producing a mask of true/false values representing
+active/inactive vector lanes, except if the VIV overflows in which case they
+return false in the lanes where the VIV overflows.  The arguments are scalar
+types to accommodate scalable vector types, for which it is unknown what the
+type of the step vector needs to be that enumerate its lanes without overflow.
 
 This mask ``%m`` can e.g. be used in masked load/store instructions. These
 intrinsics provide a hint to the backend. I.e., for a vector loop, the