XXX
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
index dcd0069..7a11293 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -256,7 +256,6 @@
   case Builtin::BI__builtin_popcountll:
   case Builtin::BI__builtin_popcountg:
     return emitBuiltinBitOp<cir::BitPopcountOp>(*this, e);
-
   case Builtin::BI__builtin_expect:
   case Builtin::BI__builtin_expect_with_probability: {
     mlir::Value argValue = emitScalarExpr(e->getArg(0));
diff --git a/mlir/include/mlir/IR/EnumAttr.td b/mlir/include/mlir/IR/EnumAttr.td
index ff6cec6..d2d0089 100644
--- a/mlir/include/mlir/IR/EnumAttr.td
+++ b/mlir/include/mlir/IR/EnumAttr.td
@@ -42,7 +42,7 @@
   let predicate = CPred<[{
     ::llvm::cast<::mlir::IntegerAttr>($_self).getValue().eq(::llvm::APInt(}]
       # intType.bitwidth # ", "
-      # intVal # 
+      # intVal #
     "))">;
 }
 
@@ -495,6 +495,11 @@
     !cast<EnumAttrInfo>(enumInfo).parameterPrinter, ?);
 }
 
+class DefaultValuedEnumParameter<EnumInfo enumInfo, EnumCase value>
+    : EnumParameter<enumInfo> {
+  let defaultValue = enumInfo.cppType # "::" # value.symbol;
+}
+
 // An attribute backed by a C++ enum. The attribute contains a single
 // parameter `value` whose type is the C++ enum class.
 //
diff --git a/mlir/test/lib/Dialect/Test/TestAttributes.h b/mlir/test/lib/Dialect/Test/TestAttributes.h
index 778d84f..6ba4e31 100644
--- a/mlir/test/lib/Dialect/Test/TestAttributes.h
+++ b/mlir/test/lib/Dialect/Test/TestAttributes.h
@@ -16,6 +16,7 @@
 
 #include <tuple>
 
+#include "TestEnums.h"
 #include "TestTraits.h"
 #include "mlir/Dialect/Ptr/IR/MemorySpaceInterfaces.h"
 #include "mlir/Dialect/Utils/StructuredOpsUtils.h"
@@ -27,7 +28,6 @@
 
 // generated files require above includes to come first
 #include "TestAttrInterfaces.h.inc"
-#include "TestOpEnums.h.inc"
 
 namespace test {
 class TestDialect;
diff --git a/mlir/test/lib/Dialect/Test/TestEnumDefs.td b/mlir/test/lib/Dialect/Test/TestEnumDefs.td
index 10e424a..6ed36c7 100644
--- a/mlir/test/lib/Dialect/Test/TestEnumDefs.td
+++ b/mlir/test/lib/Dialect/Test/TestEnumDefs.td
@@ -96,4 +96,15 @@
     MultiResultOpKind4, MultiResultOpKind5, MultiResultOpKind6
   ]>;
 
+//===----------------------------------------------------------------------===//
+// Test Enum with Default Value
+//===----------------------------------------------------------------------===//
+
+def TestDefaultCase : I32EnumAttrCase<"Default", 0, "default">;
+def NonDefaultCase : I32EnumAttrCase<"NonDefault", 1, "non_default">;
+
+def TestDefaultValuedEnum : I32Enum<"TestDefaultValuedEnum", "", [
+    TestDefaultCase, NonDefaultCase
+]>;
+
 #endif // TEST_ENUMDEFS
diff --git a/mlir/test/lib/Dialect/Test/TestEnums.h b/mlir/test/lib/Dialect/Test/TestEnums.h
new file mode 100644
index 0000000..80483d7
--- /dev/null
+++ b/mlir/test/lib/Dialect/Test/TestEnums.h
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains enum definitions for the Test dialect
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_TESTENUMS_H
+#define MLIR_TESTENUMS_H
+
+#include "mlir/IR/BuiltinAttributes.h"
+
+#include "TestOpEnums.h.inc"
+
+#endif // MLIR_TESTENUMS_H
diff --git a/mlir/test/lib/Dialect/Test/TestTypeDefs.td b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
index ea20597..7e3d648 100644
--- a/mlir/test/lib/Dialect/Test/TestTypeDefs.td
+++ b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
@@ -16,6 +16,7 @@
 // To get the test dialect def.
 include "TestDialect.td"
 include "TestAttrDefs.td"
+include "TestEnumDefs.td"
 include "TestInterfaces.td"
 include "mlir/IR/BuiltinTypes.td"
 include "mlir/Interfaces/DataLayoutInterfaces.td"
@@ -286,6 +287,15 @@
   let assemblyFormat = "`<` (`(` struct(params)^ `)`) : (`x`)? `>`";
 }
 
+def TestTypeDefaultEnumParameter
+    : Test_Type<"TestTypeDefaultEnumParameter"> {
+  let parameters = (ins
+    DefaultValuedEnumParameter<TestDefaultValuedEnum, TestDefaultCase>:$a
+  );
+  let mnemonic = "default_enum_parameter";
+  let assemblyFormat = "`<` $a `>`";
+}
+
 def TestTypeSpaces : Test_Type<"TestTypeSpaceS"> {
   let parameters = (ins "int":$a, "int":$b);
   let mnemonic = "spaces";
diff --git a/mlir/test/lib/Dialect/Test/TestTypes.h b/mlir/test/lib/Dialect/Test/TestTypes.h
index 6499a96..c220a7f 100644
--- a/mlir/test/lib/Dialect/Test/TestTypes.h
+++ b/mlir/test/lib/Dialect/Test/TestTypes.h
@@ -17,6 +17,7 @@
 #include <optional>
 #include <tuple>
 
+#include "TestEnums.h"
 #include "TestTraits.h"
 #include "mlir/Dialect/Bufferization/IR/BufferizationTypeInterfaces.h"
 #include "mlir/IR/Diagnostics.h"
diff --git a/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir b/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
index 77b9469..f17738e 100644
--- a/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
+++ b/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
@@ -77,6 +77,8 @@
 // CHECK: !test.optional_type_string
 // CHECK: !test.optional_type_string<"non default">
 // CHECK: !test.optional_type_string<"containing\0A \22escape\22 characters\0F">
+// CHECK: !test.default_enum_parameter
+// CHECK: !test.default_enum_parameter<"non_default">
 
 func.func private @test_roundtrip_default_parsers_struct(
   !test.no_parser<255, [1, 2, 3, 4, 5], "foobar", 4>
@@ -120,4 +122,6 @@
   !test.optional_type_string<"default">,
   !test.optional_type_string<"non default">,
   !test.optional_type_string<"containing\n \"escape\" characters\0f">
+  !test.default_enum_parameter,
+  !test.default_enum_parameter<"non_default">,
 )