diff --git a/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp b/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
--- a/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
+++ b/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
@@ -217,6 +217,32 @@
   return success();
 }
 
+namespace {
+class SizeEqOpConverter : public OpConversionPattern<SizeEqOp> {
+public:
+  using OpConversionPattern<SizeEqOp>::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(SizeEqOp op, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const override;
+};
+} // namespace
+
+LogicalResult
+SizeEqOpConverter::matchAndRewrite(SizeEqOp op, ArrayRef<Value> operands,
+                                   ConversionPatternRewriter &rewriter) const {
+
+  // For now, only error-free types are supported by this lowering.
+  if (!op.lhs().getType().isa<IndexType>() ||
+      !op.rhs().getType().isa<IndexType>())
+    return failure();
+
+  SizeEqOp::Adaptor transformed(operands);
+  rewriter.replaceOpWithNewOp<CmpIOp>(op, CmpIPredicate::eq, transformed.lhs(),
+                                      transformed.rhs());
+  return success();
+}
+
 namespace {
 class RankOpConverter : public OpConversionPattern<shape::RankOp> {
 public:
@@ -278,6 +304,7 @@
       GetExtentOpConverter,
       RankOpConverter,
       ShapeOfOpConversion,
+      SizeEqOpConverter,
       ToExtentTensorOpConversion>(ctx);
   // clang-format on
 }
diff --git a/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir b/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
--- a/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
+++ b/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
@@ -190,3 +190,16 @@
   // CHECK: return %[[RES]]
   return %casted : tensor<3xindex>
 }
+
+// -----
+
+// Lower `size_eq` to `cmpi`.
+// CHECK-LABEL: @size_eq
+// CHECK-SAME: (%[[A:.*]]: index, %[[B:.*]]: index) -> i1
+func @size_eq(%a : index, %b : index) -> i1 {
+  // CHECK: %[[RESULT:.*]] = cmpi "eq", %[[A]], %[[B]]
+  // CHECK: return %[[RESULT]] : i1
+  %result = shape.size_eq %a, %b : index, index
+  return %result : i1
+}
+