diff --git a/mlir/include/mlir/Dialect/Vector/IR/VectorOps.td b/mlir/include/mlir/Dialect/Vector/IR/VectorOps.td
--- a/mlir/include/mlir/Dialect/Vector/IR/VectorOps.td
+++ b/mlir/include/mlir/Dialect/Vector/IR/VectorOps.td
@@ -1751,10 +1751,16 @@
     element is read from memory. Otherwise, the corresponding element is taken
     from a 1-D pass-through vector. Informally the semantics are:
     ```
-    result[0] := mask[0] ? base[i+0] : pass_thru[0]
-    result[1] := mask[1] ? base[i+1] : pass_thru[1]
+    result[0] := if mask[0] then base[i + 0] else pass_thru[0]
+    result[1] := if mask[1] then base[i + 1] else pass_thru[1]
     etc.
     ```
+
+    If a mask bit is set and the corresponding index is out-of-bounds for the
+    given base, the behavior is undefined. If a mask bit is not set, the value
+    comes from the pass-through vector regardless of the index, and the index is
+    allowed to be out-of-bounds.
+
     The masked load can be used directly where applicable, or can be used
     during progressively lowering to bring other memory operations closer to
     hardware ISA support for a masked load. The semantics of the operation
@@ -1811,6 +1817,12 @@
     if (mask[1]) base[i+1] = value[1]
     etc.
     ```
+
+    If a mask bit is set and the corresponding index is out-of-bounds for the
+    given base, the behavior is undefined. If a mask bit is not set, no value
+    is stored regardless of the index, and the index is allowed to be
+    out-of-bounds.
+
     The masked store can be used directly where applicable, or can be used
     during progressively lowering to bring other memory operations closer to
     hardware ISA support for a masked store. The semantics of the operation
@@ -2008,12 +2020,17 @@
     is taken from a 1-D pass-through vector. Informally the semantics are:
     ```
     index = i
-    result[0] := mask[0] ? base[index++] : pass_thru[0]
-    result[1] := mask[1] ? base[index++] : pass_thru[1]
+    result[0] := if mask[0] then base[index++] else pass_thru[0]
+    result[1] := if mask[1] then base[index++] else pass_thru[1]
     etc.
     ```
     Note that the index increment is done conditionally.
 
+    If a mask bit is set and the corresponding index is out-of-bounds for the
+    given base, the behavior is undefined. If a mask bit is not set, the value
+    comes from the pass-through vector regardless of the index, and the index is
+    allowed to be out-of-bounds.
+
     The expand load can be used directly where applicable, or can be used
     during progressively lowering to bring other memory operations closer to
     hardware ISA support for an expand. The semantics of the operation closely
@@ -2072,6 +2089,11 @@
     ```
     Note that the index increment is done conditionally.
 
+    If a mask bit is set and the corresponding index is out-of-bounds for the
+    given base, the behavior is undefined. If a mask bit is not set, no value
+    is stored regardless of the index, and the index is allowed to be
+    out-of-bounds.
+
     The compress store can be used directly where applicable, or can be used
     during progressively lowering to bring other memory operations closer to
     hardware ISA support for a compress. The semantics of the operation closely