diff --git a/mlir/lib/Interfaces/DataLayoutInterfaces.cpp b/mlir/lib/Interfaces/DataLayoutInterfaces.cpp
--- a/mlir/lib/Interfaces/DataLayoutInterfaces.cpp
+++ b/mlir/lib/Interfaces/DataLayoutInterfaces.cpp
@@ -280,52 +280,48 @@
 unsigned mlir::DataLayout::getTypeSize(Type t) const {
   checkValid();
   return cachedLookup(t, sizes, [&](Type ty) {
-    if (originalLayout) {
-      DataLayoutEntryList list = originalLayout.getSpecForType(ty.getTypeID());
-      if (auto iface = dyn_cast<DataLayoutOpInterface>(scope))
-        return iface.getTypeSize(ty, *this, list);
-      return detail::getDefaultTypeSize(ty, *this, list);
-    }
-    return detail::getDefaultTypeSize(ty, *this, {});
+    DataLayoutEntryList list;
+    if (originalLayout)
+      list = originalLayout.getSpecForType(ty.getTypeID());
+    if (auto iface = dyn_cast_or_null<DataLayoutOpInterface>(scope))
+      return iface.getTypeSize(ty, *this, list);
+    return detail::getDefaultTypeSize(ty, *this, list);
   });
 }
 
 unsigned mlir::DataLayout::getTypeSizeInBits(Type t) const {
   checkValid();
   return cachedLookup(t, bitsizes, [&](Type ty) {
-    if (originalLayout) {
-      DataLayoutEntryList list = originalLayout.getSpecForType(ty.getTypeID());
-      if (auto iface = dyn_cast<DataLayoutOpInterface>(scope))
-        return iface.getTypeSizeInBits(ty, *this, list);
-      return detail::getDefaultTypeSizeInBits(ty, *this, list);
-    }
-    return detail::getDefaultTypeSizeInBits(ty, *this, {});
+    DataLayoutEntryList list;
+    if (originalLayout)
+      list = originalLayout.getSpecForType(ty.getTypeID());
+    if (auto iface = dyn_cast_or_null<DataLayoutOpInterface>(scope))
+      return iface.getTypeSizeInBits(ty, *this, list);
+    return detail::getDefaultTypeSizeInBits(ty, *this, list);
   });
 }
 
 unsigned mlir::DataLayout::getTypeABIAlignment(Type t) const {
   checkValid();
   return cachedLookup(t, abiAlignments, [&](Type ty) {
-    if (originalLayout) {
-      DataLayoutEntryList list = originalLayout.getSpecForType(ty.getTypeID());
-      if (auto iface = dyn_cast<DataLayoutOpInterface>(scope))
-        return iface.getTypeABIAlignment(ty, *this, list);
-      return detail::getDefaultABIAlignment(ty, *this, list);
-    }
-    return detail::getDefaultABIAlignment(ty, *this, {});
+    DataLayoutEntryList list;
+    if (originalLayout)
+      list = originalLayout.getSpecForType(ty.getTypeID());
+    if (auto iface = dyn_cast_or_null<DataLayoutOpInterface>(scope))
+      return iface.getTypeABIAlignment(ty, *this, list);
+    return detail::getDefaultABIAlignment(ty, *this, list);
   });
 }
 
 unsigned mlir::DataLayout::getTypePreferredAlignment(Type t) const {
   checkValid();
   return cachedLookup(t, preferredAlignments, [&](Type ty) {
-    if (originalLayout) {
-      DataLayoutEntryList list = originalLayout.getSpecForType(ty.getTypeID());
-      if (auto iface = dyn_cast<DataLayoutOpInterface>(scope))
-        return iface.getTypePreferredAlignment(ty, *this, list);
-      return detail::getDefaultPreferredAlignment(ty, *this, list);
-    }
-    return detail::getDefaultPreferredAlignment(ty, *this, {});
+    DataLayoutEntryList list;
+    if (originalLayout)
+      list = originalLayout.getSpecForType(ty.getTypeID());
+    if (auto iface = dyn_cast_or_null<DataLayoutOpInterface>(scope))
+      return iface.getTypePreferredAlignment(ty, *this, list);
+    return detail::getDefaultPreferredAlignment(ty, *this, list);
   });
 }
 
diff --git a/mlir/unittests/Interfaces/DataLayoutInterfacesTest.cpp b/mlir/unittests/Interfaces/DataLayoutInterfacesTest.cpp
--- a/mlir/unittests/Interfaces/DataLayoutInterfacesTest.cpp
+++ b/mlir/unittests/Interfaces/DataLayoutInterfacesTest.cpp
@@ -227,7 +227,7 @@
 
 TEST(DataLayout, FallbackDefault) {
   const char *ir = R"MLIR(
-"dltest.op_with_layout"() : () -> ()
+module {}
   )MLIR";
 
   DialectRegistry registry;
@@ -235,9 +235,7 @@
   MLIRContext ctx(registry);
 
   OwningModuleRef module = parseSourceString(ir, &ctx);
-  auto op =
-      cast<DataLayoutOpInterface>(module->getBody()->getOperations().front());
-  DataLayout layout(op);
+  DataLayout layout(module.get());
   EXPECT_EQ(layout.getTypeSize(IntegerType::get(&ctx, 42)), 6u);
   EXPECT_EQ(layout.getTypeSize(Float16Type::get(&ctx)), 2u);
   EXPECT_EQ(layout.getTypeSizeInBits(IntegerType::get(&ctx, 42)), 42u);
@@ -248,6 +246,29 @@
   EXPECT_EQ(layout.getTypePreferredAlignment(Float16Type::get(&ctx)), 2u);
 }
 
+TEST(DataLayout, NullSpec) {
+  const char *ir = R"MLIR(
+"dltest.op_with_layout"() : () -> ()
+  )MLIR";
+
+  DialectRegistry registry;
+  registry.insert<DLTIDialect, DLTestDialect>();
+  MLIRContext ctx(registry);
+
+  OwningModuleRef module = parseSourceString(ir, &ctx);
+  auto op =
+      cast<DataLayoutOpInterface>(module->getBody()->getOperations().front());
+  DataLayout layout(op);
+  EXPECT_EQ(layout.getTypeSize(IntegerType::get(&ctx, 42)), 42u);
+  EXPECT_EQ(layout.getTypeSize(Float16Type::get(&ctx)), 16u);
+  EXPECT_EQ(layout.getTypeSizeInBits(IntegerType::get(&ctx, 42)), 8u * 42u);
+  EXPECT_EQ(layout.getTypeSizeInBits(Float16Type::get(&ctx)), 8u * 16u);
+  EXPECT_EQ(layout.getTypeABIAlignment(IntegerType::get(&ctx, 42)), 64u);
+  EXPECT_EQ(layout.getTypeABIAlignment(Float16Type::get(&ctx)), 16u);
+  EXPECT_EQ(layout.getTypePreferredAlignment(IntegerType::get(&ctx, 42)), 128u);
+  EXPECT_EQ(layout.getTypePreferredAlignment(Float16Type::get(&ctx)), 32u);
+}
+
 TEST(DataLayout, EmptySpec) {
   const char *ir = R"MLIR(
 "dltest.op_with_layout"() { dltest.layout = #dltest.spec< > } : () -> ()