diff --git a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
--- a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
+++ b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
@@ -4945,6 +4945,21 @@
     }
   }
 
+  if (auto intPack = sourceConstant.dyn_cast<DenseIntElementsAttr>()) {
+    if (intPack.isSplat()) {
+      auto splat = intPack.getSplatValue<IntegerAttr>();
+
+      // Casting int8 into int32.
+      if (srcElemType.isInteger(8) && dstElemType.isInteger(32)) {
+        uint32_t bits = static_cast<uint32_t>(splat.getValue().getZExtValue());
+        // Duplicate the 8-bit pattern.
+        bits = (bits << 24) | (bits << 16) | (bits << 8) | bits;
+        APInt intBits(32, bits);
+        return DenseElementsAttr::get(getResultVectorType(), intBits);
+      }
+    }
+  }
+
   return {};
 }
 
diff --git a/mlir/test/Dialect/Vector/canonicalize.mlir b/mlir/test/Dialect/Vector/canonicalize.mlir
--- a/mlir/test/Dialect/Vector/canonicalize.mlir
+++ b/mlir/test/Dialect/Vector/canonicalize.mlir
@@ -741,6 +741,20 @@
   return %cast0, %cast1: vector<4xf32>, vector<4xf32>
 }
 
+// CHECK-LABEL: func @bitcast_i8_to_i32
+//              bit pattern: 0xA0A0A0A0
+//       CHECK-DAG: %[[CST1:.+]] = arith.constant dense<-1600085856> : vector<4xi32>
+//              bit pattern: 0x00000000
+//       CHECK-DAG: %[[CST0:.+]] = arith.constant dense<0> : vector<4xi32>
+//       CHECK: return %[[CST0]], %[[CST1]]
+func.func @bitcast_i8_to_i32() -> (vector<4xi32>, vector<4xi32>) {
+  %cst0 = arith.constant dense<0> : vector<16xi8> // bit pattern: 0x00
+  %cst1 = arith.constant dense<160> : vector<16xi8> // bit pattern: 0xA0
+  %cast0 = vector.bitcast %cst0: vector<16xi8> to vector<4xi32>
+  %cast1 = vector.bitcast %cst1: vector<16xi8> to vector<4xi32>
+  return %cast0, %cast1: vector<4xi32>, vector<4xi32>
+}
+
 // -----
 
 // CHECK-LABEL: broadcast_folding1