diff --git a/mlir/test/mlir-tblgen/op-result.td b/mlir/test/mlir-tblgen/op-result.td
--- a/mlir/test/mlir-tblgen/op-result.td
+++ b/mlir/test/mlir-tblgen/op-result.td
@@ -31,7 +31,7 @@
 // CHECK:   if (::mlir::succeeded(OpB::inferReturnTypes(odsBuilder.getContext(),
 // CHECK:             odsState.location, odsState.operands,
 // CHECK:             odsState.attributes.getDictionary(odsState.getContext()),
-// CHECK:             /*regions=*/{}, inferredReturnTypes)))
+// CHECK:             odsState.regions, inferredReturnTypes)))
 // CHECK:     odsState.addTypes(inferredReturnTypes);
 
 def OpC : NS_Op<"three_normal_result_op", []> {
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -1583,13 +1583,12 @@
       // Generate builder that infers type too.
       // TODO: Subsume this with general checking if type can be
       // inferred automatically.
-      // TODO: Expand to handle regions.
       body << formatv(R"(
         ::llvm::SmallVector<::mlir::Type, 2> inferredReturnTypes;
         if (::mlir::succeeded({0}::inferReturnTypes(odsBuilder.getContext(),
                       {1}.location, {1}.operands,
                       {1}.attributes.getDictionary({1}.getContext()),
-                      /*regions=*/{{}, inferredReturnTypes)))
+                      {1}.regions, inferredReturnTypes)))
           {1}.addTypes(inferredReturnTypes);
         else
           ::llvm::report_fatal_error("Failed to infer result type(s).");)",
@@ -1660,7 +1659,7 @@
   // ambiguous function detection will elide those ones.
   for (auto attrType : attrBuilderType) {
     emit(attrType, TypeParamKind::Separate, /*inferType=*/false);
-    if (canInferType(op) && op.getNumRegions() == 0)
+    if (canInferType(op))
       emit(attrType, TypeParamKind::None, /*inferType=*/true);
     emit(attrType, TypeParamKind::Collective, /*inferType=*/false);
   }