diff --git a/flang/include/flang/Optimizer/Builder/Runtime/Inquiry.h b/flang/include/flang/Optimizer/Builder/Runtime/Inquiry.h
index 5f14d7781004b..3707273e0cbd4 100644
--- a/flang/include/flang/Optimizer/Builder/Runtime/Inquiry.h
+++ b/flang/include/flang/Optimizer/Builder/Runtime/Inquiry.h
@@ -20,12 +20,14 @@ class FirOpBuilder;
 
 namespace fir::runtime {
 
-/// Generate call to general `LboundDim` runtime routine.  Calls to LBOUND
-/// without a DIM argument get transformed into descriptor inquiries so they're
-/// not handled in the runtime.
+/// Generate call to `LboundDim` runtime routine.
 mlir::Value genLboundDim(fir::FirOpBuilder &builder, mlir::Location loc,
                          mlir::Value array, mlir::Value dim);
 
+/// Generate call to Lbound` runtime routine.
+void genLbound(fir::FirOpBuilder &builder, mlir::Location loc,
+               mlir::Value resultAddr, mlir::Value arrayt, mlir::Value kind);
+
 /// Generate call to general `Ubound` runtime routine.  Calls to UBOUND
 /// with a DIM argument get transformed into an expression equivalent to
 /// SIZE() + LBOUND() - 1, so they don't have an intrinsic in the runtime.
diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
index b3e1ee3da3a77..b287b826669da 100644
--- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
@@ -6298,16 +6298,17 @@ IntrinsicLibrary::genLbound(mlir::Type resultType,
                             llvm::ArrayRef<fir::ExtendedValue> args) {
   assert(args.size() == 2 || args.size() == 3);
   const fir::ExtendedValue &array = args[0];
-  if (const auto *boxValue = array.getBoxOf<fir::BoxValue>())
-    if (boxValue->hasAssumedRank())
-      TODO(loc, "intrinsic: lbound with assumed rank argument");
+  // Semantics builds signatures for LBOUND calls as either
+  // LBOUND(array, dim, [kind]) or LBOUND(array, [kind]).
+  const bool dimIsAbsent = args.size() == 2 || isStaticallyAbsent(args, 1);
+  if (array.hasAssumedRank() && dimIsAbsent)
+    return genAssumedRankBoundInquiry(builder, loc, resultType, args,
+                                      /*kindPos=*/1, fir::runtime::genLbound);
 
   mlir::Type indexType = builder.getIndexType();
 
-  // Semantics builds signatures for LBOUND calls as either
-  // LBOUND(array, dim, [kind]) or LBOUND(array, [kind]).
-  if (args.size() == 2 || isStaticallyAbsent(args, 1)) {
-    // DIM is absent.
+  if (dimIsAbsent) {
+    // DIM is absent and the rank of array is a compile time constant.
     mlir::Type lbType = fir::unwrapSequenceType(resultType);
     unsigned rank = array.rank();
     mlir::Type lbArrayType = fir::SequenceType::get(
@@ -6332,13 +6333,16 @@ IntrinsicLibrary::genLbound(mlir::Type resultType,
   // DIM is present.
   mlir::Value dim = fir::getBase(args[1]);
 
-  // If it is a compile time constant, skip the runtime call.
-  if (std::optional<std::int64_t> cstDim = fir::getIntIfConstant(dim)) {
-    mlir::Value one = builder.createIntegerConstant(loc, resultType, 1);
-    mlir::Value zero = builder.createIntegerConstant(loc, indexType, 0);
-    mlir::Value lb = computeLBOUND(builder, loc, array, *cstDim - 1, zero, one);
-    return builder.createConvert(loc, resultType, lb);
-  }
+  // If it is a compile time constant and the rank is known, skip the runtime
+  // call.
+  if (!array.hasAssumedRank())
+    if (std::optional<std::int64_t> cstDim = fir::getIntIfConstant(dim)) {
+      mlir::Value one = builder.createIntegerConstant(loc, resultType, 1);
+      mlir::Value zero = builder.createIntegerConstant(loc, indexType, 0);
+      mlir::Value lb =
+          computeLBOUND(builder, loc, array, *cstDim - 1, zero, one);
+      return builder.createConvert(loc, resultType, lb);
+    }
 
   fir::ExtendedValue box = createBoxForRuntimeBoundInquiry(loc, builder, array);
   return builder.createConvert(
diff --git a/flang/lib/Optimizer/Builder/Runtime/Inquiry.cpp b/flang/lib/Optimizer/Builder/Runtime/Inquiry.cpp
index 34c4020b5907c..e01a6f05b5fdd 100644
--- a/flang/lib/Optimizer/Builder/Runtime/Inquiry.cpp
+++ b/flang/lib/Optimizer/Builder/Runtime/Inquiry.cpp
@@ -29,6 +29,20 @@ mlir::Value fir::runtime::genLboundDim(fir::FirOpBuilder &builder,
   return builder.create<fir::CallOp>(loc, lboundFunc, args).getResult(0);
 }
 
+void fir::runtime::genLbound(fir::FirOpBuilder &builder, mlir::Location loc,
+                             mlir::Value resultAddr, mlir::Value array,
+                             mlir::Value kind) {
+  mlir::func::FuncOp func =
+      fir::runtime::getRuntimeFunc<mkRTKey(Lbound)>(loc, builder);
+  auto fTy = func.getFunctionType();
+  auto sourceFile = fir::factory::locationToFilename(builder, loc);
+  auto sourceLine =
+      fir::factory::locationToLineNo(builder, loc, fTy.getInput(4));
+  auto args = fir::runtime::createArguments(
+      builder, loc, fTy, resultAddr, array, kind, sourceFile, sourceLine);
+  builder.create<fir::CallOp>(loc, func, args).getResult(0);
+}
+
 /// Generate call to `Ubound` runtime routine.  Calls to UBOUND with a DIM
 /// argument get transformed into an expression equivalent to
 /// SIZE() + LBOUND() - 1, so they don't have an intrinsic in the runtime.
diff --git a/flang/test/Lower/HLFIR/assumed-rank-inquiries-3.f90 b/flang/test/Lower/HLFIR/assumed-rank-inquiries-3.f90
index bbeff5ff05191..e568b94f4f884 100644
--- a/flang/test/Lower/HLFIR/assumed-rank-inquiries-3.f90
+++ b/flang/test/Lower/HLFIR/assumed-rank-inquiries-3.f90
@@ -54,3 +54,58 @@ subroutine test_shape_2(x)
 ! CHECK:           %[[VAL_13:.*]] = fir.box_rank %[[VAL_4]] : (!fir.box<!fir.ptr<!fir.array<*:f32>>>) -> index
 ! CHECK:           %[[VAL_14:.*]] = fir.shape %[[VAL_13]] : (index) -> !fir.shape<1>
 ! CHECK:           %[[VAL_15:.*]]:2 = hlfir.declare %[[VAL_12]](%[[VAL_14]]) {uniq_name = ".tmp.intrinsic_result"} : (!fir.ref<!fir.array<?xi32>>, !fir.shape<1>) -> (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?xi32>>)
+
+
+subroutine test_lbound(x)
+  real :: x(..)
+  call takes_integer_array(lbound(x))
+end subroutine
+! CHECK-LABEL:   func.func @_QPtest_lbound(
+! CHECK:           %[[VAL_1:.*]] = fir.alloca !fir.array<15xi32>
+! CHECK:           %[[VAL_4:.*]] = arith.constant 4 : i32
+! CHECK:           %[[VAL_7:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi32>>) -> !fir.llvm_ptr<i8>
+! CHECK:           %[[VAL_8:.*]] = fir.convert %[[VAL_3:.*]] : (!fir.box<!fir.array<*:f32>>) -> !fir.box<none>
+! CHECK:           %[[VAL_10:.*]] = fir.call @_FortranALbound(%[[VAL_7]], %[[VAL_8]], %[[VAL_4]], %{{.*}}, %{{.*}})
+! CHECK:           %[[VAL_11:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi32>>) -> !fir.ref<!fir.array<?xi32>>
+! CHECK:           %[[VAL_12:.*]] = fir.box_rank %[[VAL_3]] : (!fir.box<!fir.array<*:f32>>) -> index
+! CHECK:           %[[VAL_13:.*]] = fir.shape %[[VAL_12]] : (index) -> !fir.shape<1>
+! CHECK:           %[[VAL_14:.*]]:2 = hlfir.declare %[[VAL_11]](%[[VAL_13]]) {uniq_name = ".tmp.intrinsic_result"} : (!fir.ref<!fir.array<?xi32>>, !fir.shape<1>) -> (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?xi32>>)
+! CHECK:           %[[VAL_15:.*]] = arith.constant false
+! CHECK:           %[[VAL_16:.*]] = hlfir.as_expr %[[VAL_14]]#0 move %[[VAL_15]] : (!fir.box<!fir.array<?xi32>>, i1) -> !hlfir.expr<?xi32>
+! CHECK:           %[[VAL_17:.*]]:3 = hlfir.associate %[[VAL_16]](%[[VAL_13]]) {adapt.valuebyref} : (!hlfir.expr<?xi32>, !fir.shape<1>) -> (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?xi32>>, i1)
+! CHECK:           fir.call @_QPtakes_integer_array(%[[VAL_17]]#1) fastmath<contract> : (!fir.ref<!fir.array<?xi32>>) -> ()
+! CHECK:           hlfir.end_associate %[[VAL_17]]#1, %[[VAL_17]]#2 : !fir.ref<!fir.array<?xi32>>, i1
+! CHECK:           hlfir.destroy %[[VAL_16]] : !hlfir.expr<?xi32>
+! CHECK:           return
+! CHECK:         }
+
+subroutine test_lbound_kind(x)
+  real :: x(..)
+  call takes_integer8_array(lbound(x, kind=8))
+end subroutine
+! CHECK-LABEL:   func.func @_QPtest_lbound_kind(
+! CHECK:           %[[VAL_1:.*]] = fir.alloca !fir.array<15xi64>
+! CHECK:           %[[VAL_4:.*]] = arith.constant 8 : i32
+! CHECK:           %[[VAL_7:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi64>>) -> !fir.llvm_ptr<i8>
+! CHECK:           %[[VAL_8:.*]] = fir.convert %[[VAL_3:.*]] : (!fir.box<!fir.array<*:f32>>) -> !fir.box<none>
+! CHECK:           %[[VAL_10:.*]] = fir.call @_FortranALbound(%[[VAL_7]], %[[VAL_8]], %[[VAL_4]], %{{.*}}, %{{.*}})
+! CHECK:           %[[VAL_11:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi64>>) -> !fir.ref<!fir.array<?xi64>>
+! CHECK:           %[[VAL_12:.*]] = fir.box_rank %[[VAL_3]] : (!fir.box<!fir.array<*:f32>>) -> index
+! CHECK:           %[[VAL_13:.*]] = fir.shape %[[VAL_12]] : (index) -> !fir.shape<1>
+! CHECK:           %[[VAL_14:.*]]:2 = hlfir.declare %[[VAL_11]](%[[VAL_13]]) {uniq_name = ".tmp.intrinsic_result"} : (!fir.ref<!fir.array<?xi64>>, !fir.shape<1>) -> (!fir.box<!fir.array<?xi64>>, !fir.ref<!fir.array<?xi64>>)
+
+subroutine test_lbound_2(x)
+  real, pointer :: x(..)
+  call takes_integer_array(lbound(x))
+end subroutine
+! CHECK-LABEL:   func.func @_QPtest_lbound_2(
+! CHECK:           %[[VAL_1:.*]] = fir.alloca !fir.array<15xi32>
+! CHECK:           %[[VAL_4:.*]] = fir.load %[[VAL_3:.*]] : !fir.ref<!fir.box<!fir.ptr<!fir.array<*:f32>>>>
+! CHECK:           %[[VAL_5:.*]] = arith.constant 4 : i32
+! CHECK:           %[[VAL_8:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi32>>) -> !fir.llvm_ptr<i8>
+! CHECK:           %[[VAL_9:.*]] = fir.convert %[[VAL_4]] : (!fir.box<!fir.ptr<!fir.array<*:f32>>>) -> !fir.box<none>
+! CHECK:           %[[VAL_11:.*]] = fir.call @_FortranALbound(%[[VAL_8]], %[[VAL_9]], %[[VAL_5]], %{{.*}}, %{{.*}})
+! CHECK:           %[[VAL_12:.*]] = fir.convert %[[VAL_1]] : (!fir.ref<!fir.array<15xi32>>) -> !fir.ref<!fir.array<?xi32>>
+! CHECK:           %[[VAL_13:.*]] = fir.box_rank %[[VAL_4]] : (!fir.box<!fir.ptr<!fir.array<*:f32>>>) -> index
+! CHECK:           %[[VAL_14:.*]] = fir.shape %[[VAL_13]] : (index) -> !fir.shape<1>
+! CHECK:           %[[VAL_15:.*]]:2 = hlfir.declare %[[VAL_12]](%[[VAL_14]]) {uniq_name = ".tmp.intrinsic_result"} : (!fir.ref<!fir.array<?xi32>>, !fir.shape<1>) -> (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?xi32>>)