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
@@ -104,6 +104,21 @@
   }
 };
 
+class SizeEqOpConverter : public OpConversionPattern<SizeEqOp> {
+public:
+  using OpConversionPattern<SizeEqOp>::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(SizeEqOp op, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const override {
+
+    SizeEqOp::Adaptor transformed(operands);
+    rewriter.replaceOpWithNewOp<CmpIOp>(op, CmpIPredicate::eq,
+                                        transformed.lhs(), transformed.rhs());
+    return success();
+  }
+};
+
 /// Type conversions.
 class ShapeTypeConverter : public TypeConverter {
 public:
@@ -162,7 +177,8 @@
       BinaryOpConversion<MulOp, MulIOp>,
       ConstSizeOpConverter,
       RankOpConverter,
-      ShapeOfOpConversion>(ctx);
+      ShapeOfOpConversion,
+      SizeEqOpConverter>(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
@@ -127,3 +127,15 @@
   %rank = shape.rank %shape
   return %rank : !shape.size
 }
+
+// -----
+
+// Lower `size_eq` to `cmpi`.
+// CHECK-LABEL: @size_eq
+// CHECK-SAME: (%[[A:.*]]: index, %[[B:.*]]: index) -> i1
+func @size_eq(%a : !shape.size, %b : !shape.size) -> i1 {
+  // CHECK: %[[RESULT:.*]] = cmpi "eq", %[[A]], %[[B]]
+  // CHECK: return %[[RESULT]] : i1
+  %result = shape.size_eq %a, %b
+  return %result : i1
+}