diff --git a/flang/lib/Optimizer/Builder/FIRBuilder.cpp b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
index ae82a5afa2acb..ae46287ea3c2c 100644
--- a/flang/lib/Optimizer/Builder/FIRBuilder.cpp
+++ b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
@@ -1468,6 +1468,17 @@ fir::BoxValue fir::factory::createBoxValue(fir::FirOpBuilder &builder,
         explicitTypeParams.emplace_back(box.getLen());
       },
       [&](const fir::MutableBoxValue &x) {
+        if (x.rank() > 0) {
+          // The resulting box lbounds must be coming from the mutable box.
+          fir::ExtendedValue boxVal =
+              fir::factory::genMutableBoxRead(builder, loc, x);
+          // Make sure we do not recurse infinitely.
+          if (boxVal.getBoxOf<fir::MutableBoxValue>())
+            fir::emitFatalError(loc, "mutable box read cannot be mutable box");
+          fir::BoxValue box =
+              fir::factory::createBoxValue(builder, loc, boxVal);
+          lbounds.append(box.getLBounds().begin(), box.getLBounds().end());
+        }
         explicitTypeParams.append(x.nonDeferredLenParams().begin(),
                                   x.nonDeferredLenParams().end());
       },
diff --git a/flang/test/Lower/HLFIR/select-type-selector.f90 b/flang/test/Lower/HLFIR/select-type-selector.f90
new file mode 100644
index 0000000000000..a9536c9ccee69
--- /dev/null
+++ b/flang/test/Lower/HLFIR/select-type-selector.f90
@@ -0,0 +1,61 @@
+! Test that the selector is lowered as a box with the lower
+! bounds inherited from the original variable. Otherwise,
+! the bounds accessed inside the type guard block are going
+! to be default 1-based.
+!
+! 11.1.11.2 Execution of the SELECT TYPE construct
+! 5 Within the block following a TYPE IS type guard statement, the associating entity (19.5.5) is not polymorphic
+! (7.3.2.3), has the type named in the type guard statement, and has the type parameter values of the selector.
+! 8 The other attributes of the associating entity are described in 11.1.3.3.
+! ...
+! 11.1.3.3 Other attributes of associate names
+! 1 Within an ASSOCIATE, CHANGE TEAM, or SELECT TYPE construct, each associating entity has the same
+! rank as its associated selector. The lower bound of each dimension is the result of the intrinsic function LBOUND
+! (16.9.109) applied to the corresponding dimension of selector. The upper bound of each dimension is one less
+! than the sum of the lower bound and the extent.
+
+! RUN: bbc -emit-hlfir -polymorphic-type -I nowhere -o - %s | FileCheck %s
+
+subroutine test()
+  type t
+  end type t
+  class(*), allocatable :: x(:)
+  integer :: ub
+!  allocate(x(-1:8))
+  select type(x)
+  type is (t)
+     ub = ubound(x, 1)
+  end select
+end subroutine test
+! CHECK-LABEL:   func.func @_QPtest() {
+! CHECK:           %[[VAL_0:.*]] = fir.alloca i32 {bindc_name = "ub", uniq_name = "_QFtestEub"}
+! CHECK:           %[[VAL_1:.*]]:2 = hlfir.declare %[[VAL_0]] {uniq_name = "_QFtestEub"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+! CHECK:           %[[VAL_2:.*]] = fir.alloca !fir.class<!fir.heap<!fir.array<?xnone>>> {bindc_name = "x", uniq_name = "_QFtestEx"}
+! CHECK:           %[[VAL_3:.*]] = fir.zero_bits !fir.heap<!fir.array<?xnone>>
+! CHECK:           %[[VAL_4:.*]] = arith.constant 0 : index
+! CHECK:           %[[VAL_5:.*]] = fir.shape %[[VAL_4]] : (index) -> !fir.shape<1>
+! CHECK:           %[[VAL_6:.*]] = fir.embox %[[VAL_3]](%[[VAL_5]]) : (!fir.heap<!fir.array<?xnone>>, !fir.shape<1>) -> !fir.class<!fir.heap<!fir.array<?xnone>>>
+! CHECK:           fir.store %[[VAL_6]] to %[[VAL_2]] : !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>
+! CHECK:           %[[VAL_7:.*]]:2 = hlfir.declare %[[VAL_2]] {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFtestEx"} : (!fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>) -> (!fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>, !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>)
+! CHECK:           %[[VAL_8:.*]] = fir.load %[[VAL_7]]#1 : !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>
+! CHECK:           %[[VAL_9:.*]] = fir.load %[[VAL_7]]#1 : !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>
+! CHECK:           %[[VAL_10:.*]] = arith.constant 0 : index
+! CHECK:           %[[VAL_11:.*]]:3 = fir.box_dims %[[VAL_9]], %[[VAL_10]] : (!fir.class<!fir.heap<!fir.array<?xnone>>>, index) -> (index, index, index)
+! CHECK:           fir.select_type %[[VAL_8]] : !fir.class<!fir.heap<!fir.array<?xnone>>> [#fir.type_is<!fir.type<_QFtestTt>>, ^bb1, unit, ^bb2]
+! CHECK:         ^bb1:
+! CHECK:           %[[VAL_12:.*]] = fir.convert %[[VAL_8]] : (!fir.class<!fir.heap<!fir.array<?xnone>>>) -> !fir.box<!fir.heap<!fir.array<?x!fir.type<_QFtestTt>>>>
+! CHECK:           %[[VAL_13:.*]] = fir.shift %[[VAL_11]]#0 : (index) -> !fir.shift<1>
+! CHECK:           %[[VAL_14:.*]]:2 = hlfir.declare %[[VAL_12]](%[[VAL_13]]) {uniq_name = "_QFtestEx"} : (!fir.box<!fir.heap<!fir.array<?x!fir.type<_QFtestTt>>>>, !fir.shift<1>) -> (!fir.box<!fir.heap<!fir.array<?x!fir.type<_QFtestTt>>>>, !fir.box<!fir.heap<!fir.array<?x!fir.type<_QFtestTt>>>>)
+! CHECK:           %[[VAL_15:.*]] = arith.constant 0 : index
+! CHECK:           %[[VAL_16:.*]]:3 = fir.box_dims %[[VAL_14]]#0, %[[VAL_15]] : (!fir.box<!fir.heap<!fir.array<?x!fir.type<_QFtestTt>>>>, index) -> (index, index, index)
+! CHECK:           %[[VAL_17:.*]] = fir.convert %[[VAL_16]]#1 : (index) -> i64
+! CHECK:           %[[VAL_18:.*]] = fir.convert %[[VAL_11]]#0 : (index) -> i64
+! CHECK:           %[[VAL_19:.*]] = arith.addi %[[VAL_17]], %[[VAL_18]] : i64
+! CHECK:           %[[VAL_20:.*]] = arith.constant 1 : i64
+! CHECK:           %[[VAL_21:.*]] = arith.subi %[[VAL_19]], %[[VAL_20]] : i64
+! CHECK:           %[[VAL_22:.*]] = fir.convert %[[VAL_21]] : (i64) -> i32
+! CHECK:           hlfir.assign %[[VAL_22]] to %[[VAL_1]]#0 : i32, !fir.ref<i32>
+! CHECK:           cf.br ^bb2
+! CHECK:         ^bb2:
+! CHECK:           return
+! CHECK:         }