diff --git a/flang/include/flang/Semantics/tools.h b/flang/include/flang/Semantics/tools.h
--- a/flang/include/flang/Semantics/tools.h
+++ b/flang/include/flang/Semantics/tools.h
@@ -186,6 +186,7 @@
 bool HasCoarray(const parser::Expr &);
 bool IsAssumedType(const Symbol &);
 bool IsPolymorphic(const Symbol &);
+bool IsUnlimitedPolymorphic(const Symbol &);
 bool IsPolymorphicAllocatable(const Symbol &);
 
 // Return an error if a symbol is not accessible from a scope
diff --git a/flang/lib/Lower/ConvertVariable.cpp b/flang/lib/Lower/ConvertVariable.cpp
--- a/flang/lib/Lower/ConvertVariable.cpp
+++ b/flang/lib/Lower/ConvertVariable.cpp
@@ -625,6 +625,11 @@
     return false;
   if (Fortran::semantics::IsDummy(sym) && !Fortran::semantics::IsIntentOut(sym))
     return false;
+  // Unlimited polymorphic intent(out) dummy might need default initialization
+  // at runtime but it cannot be determined for sure here.
+  if (Fortran::semantics::IsUnlimitedPolymorphic(sym) &&
+      Fortran::semantics::IsDummy(sym) && Fortran::semantics::IsIntentOut(sym))
+    return true;
   // Local variables (including function results), and intent(out) dummies must
   // be default initialized at runtime if their type has default initialization.
   return hasDefaultInitialization(sym);
diff --git a/flang/lib/Semantics/tools.cpp b/flang/lib/Semantics/tools.cpp
--- a/flang/lib/Semantics/tools.cpp
+++ b/flang/lib/Semantics/tools.cpp
@@ -961,6 +961,13 @@
   return false;
 }
 
+bool IsUnlimitedPolymorphic(const Symbol &symbol) {
+  if (const DeclTypeSpec * type{symbol.GetType()}) {
+    return type->IsUnlimitedPolymorphic();
+  }
+  return false;
+}
+
 bool IsPolymorphicAllocatable(const Symbol &symbol) {
   return IsAllocatable(symbol) && IsPolymorphic(symbol);
 }
diff --git a/flang/test/Lower/polymorphic.f90 b/flang/test/Lower/polymorphic.f90
--- a/flang/test/Lower/polymorphic.f90
+++ b/flang/test/Lower/polymorphic.f90
@@ -738,6 +738,15 @@
 ! CHECK: %[[RES:.*]] = fir.call @_QMpolymorphic_testPunlimited_polymorphic_alloc_array_ret() fastmath<contract> : () -> !fir.class<!fir.heap<!fir.array<?xnone>>>
 ! CHECK: fir.save_result %[[RES]] to %[[RES_TMP]] : !fir.class<!fir.heap<!fir.array<?xnone>>>, !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>
 
+  subroutine test_unlimited_polymorphic_intentout(a)
+    class(*), intent(out) :: a
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPtest_unlimited_polymorphic_intentout(
+! CHECK-SAME: %[[ARG0:.*]]: !fir.class<none> {fir.bindc_name = "a"}) {
+! CHECK: %[[BOX_NONE:.*]] = fir.convert %[[ARG0]] : (!fir.class<none>) -> !fir.box<none>
+! CHECK: %{{.*}} = fir.call @_FortranAInitialize(%[[BOX_NONE]], %{{.*}}, %{{.*}}) {{.*}} : (!fir.box<none>, !fir.ref<i8>, i32) -> none
+
 end module
 
 program test