diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -1554,9 +1554,8 @@
                        mlir::Value typeDesc = {}) const {
     auto loc = box.getLoc();
     auto boxTy = box.getType().template dyn_cast<fir::BaseBoxType>();
-    bool isUnlimitedPolymorphic = fir::isUnlimitedPolymorphicType(boxTy);
-    bool useInputType =
-        isUnlimitedPolymorphic && !fir::isUnlimitedPolymorphicType(inputType);
+    bool useInputType = fir::isPolymorphicType(boxTy) &&
+                        !fir::isUnlimitedPolymorphicType(inputType);
     llvm::SmallVector<mlir::Value> typeparams = lenParams;
     if constexpr (!std::is_same_v<BOX, fir::EmboxOp>) {
       if (!box.getSubstr().empty() && fir::hasDynamicSize(boxTy.getEleTy()))
@@ -1564,8 +1563,9 @@
     }
 
     // Write each of the fields with the appropriate values.
-    // When emboxing an element to a unlimited polymorphic descriptor, use the
-    // input type since the destination descriptor type as no type information.
+    // When emboxing an element to a polymorphic descriptor, use the
+    // input type since the destination descriptor type has not the exact
+    // information.
     auto [eleSize, cfiTy] = getSizeAndTypeCode(
         loc, rewriter, useInputType ? inputType : boxTy.getEleTy(), typeparams);
     auto mod = box->template getParentOfType<mlir::ModuleOp>();
@@ -1589,10 +1589,10 @@
     auto [eleSize, cfiTy] =
         getSizeAndTypeCode(loc, rewriter, boxTy.getEleTy(), typeparams);
 
-    // Reboxing an unlimited polymorphic entities. eleSize and type code need to
-    // be retrived from the initial box.
-    if (fir::isUnlimitedPolymorphicType(boxTy) &&
-        fir::isUnlimitedPolymorphicType(box.getBox().getType())) {
+    // Reboxing a polymorphic entities. eleSize and type code need to
+    // be retrived from the initial box and propagated to the new box.
+    if (fir::isPolymorphicType(boxTy) &&
+        fir::isPolymorphicType(box.getBox().getType())) {
       mlir::Type idxTy = this->lowerTy().indexType();
       eleSize = this->loadElementSizeFromBox(loc, idxTy, loweredBox, rewriter);
       cfiTy = this->getValueFromBox(loc, loweredBox, cfiTy.getType(), rewriter,
diff --git a/flang/test/Lower/allocatable-polymorphic.f90 b/flang/test/Lower/allocatable-polymorphic.f90
--- a/flang/test/Lower/allocatable-polymorphic.f90
+++ b/flang/test/Lower/allocatable-polymorphic.f90
@@ -408,18 +408,28 @@
 ! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[C1_LOAD]], ptr %{{.*}}
 ! LLVM: %[[GEP_TDESC_C1:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.*}}, i32 0, i32 7
 ! LLVM: %[[TDESC_C1:.*]] = load ptr, ptr %[[GEP_TDESC_C1]]
-! LLVM: %[[BOX0:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr undef, i64 ptrtoint (ptr getelementptr (%_QMpolyTp1, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr undef, [1 x i64] undef }, ptr %[[TDESC_C1]], 7
-! LLVM: %[[BOX1:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX0]], ptr %{{.*}}, 0
-! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX1]], ptr %[[TMP:.*]]
+! LLVM: %[[ELEM_SIZE_GEP:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.}}, i32 0, i32 1
+! LLVM: %[[ELEM_SIZE:.*]] = load i64, ptr %[[ELEM_SIZE_GEP]]
+! LLVM: %[[TYPE_CODE_GEP:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.}}, i32 0, i32 4
+! LLVM: %[[TYPE_CODE:.*]] = load i32, ptr %[[TYPE_CODE_GEP]]
+! LLVM: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } undef, i64 %[[ELEM_SIZE]], 1
+! LLVM: %[[TRUNC_TYPE_CODE:.*]] = trunc i32 %[[TYPE_CODE]] to i8 
+! LLVM: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, i8 %[[TRUNC_TYPE_CODE]], 4
+! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, ptr %[[TMP:.*]]
 ! LLVM: call void %{{.*}}(ptr %{{.*}}) 
 
 ! LLVM: %[[LOAD_C2:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.*}}
 ! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOAD_C2]], ptr %{{.*}}
 ! LLVM: %[[GEP_TDESC_C2:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.*}}, i32 0, i32 7
 ! LLVM: %[[TDESC_C2:.*]] = load ptr, ptr %[[GEP_TDESC_C2]]
-! LLVM: %[[BOX0:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr undef, i64 ptrtoint (ptr getelementptr (%_QMpolyTp1, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr undef, [1 x i64] undef }, ptr %[[TDESC_C2]], 7
-! LLVM: %[[BOX1:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX0]], ptr %{{.*}}, 0
-! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX1]], ptr %{{.*}}
+! LLVM: %[[ELEM_SIZE_GEP:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.}}, i32 0, i32 1
+! LLVM: %[[ELEM_SIZE:.*]] = load i64, ptr %[[ELEM_SIZE_GEP]]
+! LLVM: %[[TYPE_CODE_GEP:.*]] = getelementptr { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %{{.}}, i32 0, i32 4
+! LLVM: %[[TYPE_CODE:.*]] = load i32, ptr %[[TYPE_CODE_GEP]]
+! LLVM: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } undef, i64 %[[ELEM_SIZE]], 1
+! LLVM: %[[TRUNC_TYPE_CODE:.*]] = trunc i32 %[[TYPE_CODE]] to i8 
+! LLVM: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, i8 %[[TRUNC_TYPE_CODE]], 4
+! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, ptr %{{.*}}
 ! LLVM: call void %{{.*}}(ptr %{{.*}})
 
 ! LLVM: %[[C3_LOAD:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, [1 x [3 x i64]], ptr, [1 x i64] }, ptr %{{.*}}