diff --git a/mlir/lib/IR/StandardTypes.cpp b/mlir/lib/IR/StandardTypes.cpp
--- a/mlir/lib/IR/StandardTypes.cpp
+++ b/mlir/lib/IR/StandardTypes.cpp
@@ -230,6 +230,11 @@
   if (elementType.isIntOrFloat())
     return elementType.getIntOrFloatBitWidth() * getNumElements();
 
+  if (auto complexType = elementType.dyn_cast<ComplexType>()) {
+    elementType = complexType.getElementType();
+    return elementType.getIntOrFloatBitWidth() * getNumElements() * 2;
+  }
+
   // Tensors can have vectors and other tensors as elements, other shaped types
   // cannot.
   assert(isa<TensorType>() && "unsupported element type");
diff --git a/mlir/test/mlir-tblgen/op-derived-attribute.mlir b/mlir/test/mlir-tblgen/op-derived-attribute.mlir
--- a/mlir/test/mlir-tblgen/op-derived-attribute.mlir
+++ b/mlir/test/mlir-tblgen/op-derived-attribute.mlir
@@ -5,9 +5,14 @@
   // expected-remark @+2 {{element_dtype = f32}}
   // expected-remark @+1 {{size = 320}}
   %0 = "test.derived_type_attr"() : () -> tensor<10xf32>
+
   // expected-remark @+2 {{element_dtype = i79}}
   // expected-remark @+1 {{size = 948}}
   %1 = "test.derived_type_attr"() : () -> tensor<12xi79>
 
+  // expected-remark @+2 {{element_dtype = complex<f32>}}
+  // expected-remark @+1 {{size = 768}}
+  %2 = "test.derived_type_attr"() : () -> tensor<12xcomplex<f32>>
+
   return
 }