diff --git a/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td b/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
--- a/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
+++ b/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
@@ -531,6 +531,8 @@
     %a = complex.sub %b, %c : complex<f32>
     ```
   }];
+
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
--- a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
+++ b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
@@ -138,6 +138,21 @@
   return {};
 }
 
+//===----------------------------------------------------------------------===//
+// SubOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult SubOp::fold(ArrayRef<Attribute> operands) {
+  assert(operands.size() == 2 && "binary op takes 2 operands");
+
+  // complex.sub(complex.add(a, b), b) -> a
+  if (auto add = getLhs().getDefiningOp<AddOp>())
+    if (getRhs() == add.getRhs())
+      return add.getLhs();
+
+  return {};
+}
+
 //===----------------------------------------------------------------------===//
 // NegOp
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/Dialect/Complex/canonicalize.mlir b/mlir/test/Dialect/Complex/canonicalize.mlir
--- a/mlir/test/Dialect/Complex/canonicalize.mlir
+++ b/mlir/test/Dialect/Complex/canonicalize.mlir
@@ -133,4 +133,15 @@
   // CHECK-NEXT: return %[[CPLX:.*]] : complex<f32>
   %add = complex.add %complex1, %complex2 : complex<f32>
   return %add : complex<f32>
+}
+
+// CHECK-LABEL: func @complex_sub_add_lhs
+func.func @complex_sub_add_lhs() -> complex<f32> {
+  %complex1 = complex.constant [1.0 : f32, 0.0 : f32] : complex<f32>
+  %complex2 = complex.constant [0.0 : f32, 2.0 : f32] : complex<f32>
+  // CHECK: %[[CPLX:.*]] = complex.constant [1.000000e+00 : f32, 0.000000e+00 : f32] : complex<f32>
+  // CHECK-NEXT: return %[[CPLX:.*]] : complex<f32>
+  %add = complex.add %complex1, %complex2 : complex<f32>
+  %sub = complex.sub %add, %complex2 : complex<f32>
+  return %sub : complex<f32>
 }
\ No newline at end of file