diff --git a/flang/lib/Optimizer/Dialect/FIRType.cpp b/flang/lib/Optimizer/Dialect/FIRType.cpp
--- a/flang/lib/Optimizer/Dialect/FIRType.cpp
+++ b/flang/lib/Optimizer/Dialect/FIRType.cpp
@@ -265,8 +265,21 @@
 bool isUnlimitedPolymorphicType(mlir::Type ty) {
   if (auto refTy = fir::dyn_cast_ptrEleTy(ty))
     ty = refTy;
-  if (auto clTy = ty.dyn_cast<fir::ClassType>())
-    return clTy.getEleTy().isa<mlir::NoneType>();
+  if (auto clTy = ty.dyn_cast<fir::ClassType>()) {
+    if (clTy.getEleTy().isa<mlir::NoneType>())
+      return true;
+    mlir::Type innerType =
+        llvm::TypeSwitch<mlir::Type, mlir::Type>(clTy.getEleTy())
+            .Case<fir::PointerType, fir::HeapType, fir::SequenceType>(
+                [](auto ty) {
+                  mlir::Type eleTy = ty.getEleTy();
+                  if (auto seqTy = eleTy.dyn_cast<fir::SequenceType>())
+                    return seqTy.getEleTy();
+                  return eleTy;
+                })
+            .Default([](mlir::Type) { return mlir::Type{}; });
+    return innerType.isa<mlir::NoneType>();
+  }
   return false;
 }
 
diff --git a/flang/unittests/Optimizer/CMakeLists.txt b/flang/unittests/Optimizer/CMakeLists.txt
--- a/flang/unittests/Optimizer/CMakeLists.txt
+++ b/flang/unittests/Optimizer/CMakeLists.txt
@@ -23,6 +23,7 @@
   Builder/Runtime/StopTest.cpp
   Builder/Runtime/TransformationalTest.cpp
   FIRContextTest.cpp
+  FIRTypesTest.cpp
   InternalNamesTest.cpp
   KindMappingTest.cpp
   RTBuilder.cpp
diff --git a/flang/unittests/Optimizer/FIRTypesTest.cpp b/flang/unittests/Optimizer/FIRTypesTest.cpp
new file mode 100644
--- /dev/null
+++ b/flang/unittests/Optimizer/FIRTypesTest.cpp
@@ -0,0 +1,61 @@
+//===- FIRTypesTest.cpp ---------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Optimizer/Support/InitFIR.h"
+
+struct FIRTypesTest : public testing::Test {
+public:
+  void SetUp() { fir::support::loadDialects(context); }
+
+  mlir::MLIRContext context;
+};
+
+// Test fir::isUnlimitedPolymorphicType from flang/Optimizer/Dialect/FIRType.h.
+TEST_F(FIRTypesTest, isUnlimitedPolymorphicTypeTest) {
+  mlir::Type noneTy = mlir::NoneType::get(&context);
+
+  // CLASS(*)
+  mlir::Type ty = fir::ClassType::get(noneTy);
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(fir::ReferenceType::get(ty)));
+
+  // CLASS(*), DIMENSION(10)
+  ty = fir::ClassType::get(fir::SequenceType::get({10}, noneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  // CLASS(*), DIMENSION(:)
+  ty = fir::ClassType::get(
+      fir::SequenceType::get({fir::SequenceType::getUnknownExtent()}, noneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  // CLASS(*), ALLOCATABLE
+  ty = fir::ClassType::get(fir::HeapType::get(noneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  mlir::Type seqNoneTy =
+      fir::SequenceType::get({fir::SequenceType::getUnknownExtent()}, noneTy);
+  // CLASS(*), ALLOCATABLE, DIMENSION(:)
+  ty = fir::ClassType::get(fir::HeapType::get(seqNoneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  // CLASS(*), POINTER
+  ty = fir::ClassType::get(fir::PointerType::get(noneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  // CLASS(*), POINTER, DIMENSIONS(:)
+  ty = fir::ClassType::get(fir::PointerType::get(seqNoneTy));
+  EXPECT_TRUE(fir::isUnlimitedPolymorphicType(ty));
+
+  // false tests
+  EXPECT_FALSE(fir::isUnlimitedPolymorphicType(noneTy));
+  EXPECT_FALSE(fir::isUnlimitedPolymorphicType(fir::BoxType::get(noneTy)));
+  EXPECT_FALSE(fir::isUnlimitedPolymorphicType(fir::BoxType::get(seqNoneTy)));
+  EXPECT_FALSE(fir::isUnlimitedPolymorphicType(seqNoneTy));
+}