Index: flang/lib/Lower/OpenMP.cpp
===================================================================
--- flang/lib/Lower/OpenMP.cpp
+++ flang/lib/Lower/OpenMP.cpp
@@ -1214,7 +1214,9 @@
     TypeRange resultType;
     auto SimdLoopOp = firOpBuilder.create<mlir::omp::SimdLoopOp>(
         currentLocation, resultType, lowerBound, upperBound, step, alignedVars,
-        nullptr, ifClauseOperand, simdlenClauseOperand, safelenClauseOperand,
+        nullptr, ifClauseOperand,
+        orderClauseOperand.dyn_cast_or_null<omp::ClauseOrderKindAttr>(),
+        simdlenClauseOperand, safelenClauseOperand,
         /*inclusive=*/firOpBuilder.getUnitAttr());
     createBodyOfOp<omp::SimdLoopOp>(SimdLoopOp, converter, currentLocation,
                                     eval, &loopOpClauseList, iv);
Index: mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
===================================================================
--- mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
+++ mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
@@ -393,6 +393,10 @@
     iterations to be executed concurrently is one, regardless of whether
     a simdlen clause is specified.
 
+    The optional `order` attribute specifies which order the iterations of the
+    associate loops are executed in. Currently the only option for this
+    attribute is "concurrent".
+
     When a simdlen clause is present, the preferred number of iterations to be
     executed concurrently is the value provided to the simdlen clause.
 
@@ -415,6 +419,7 @@
              Variadic<OpenMP_PointerLikeType>:$aligned_vars,
              OptionalAttr<I64ArrayAttr>:$alignment_values,
              Optional<I1>:$if_expr,
+             OptionalAttr<OrderKindAttr>:$order_val,
              ConfinedAttr<OptionalAttr<I64Attr>, [IntPositive]>:$simdlen,
              ConfinedAttr<OptionalAttr<I64Attr>, [IntPositive]>:$safelen,
              UnitAttr:$inclusive
@@ -426,6 +431,7 @@
               custom<AlignedClause>($aligned_vars, type($aligned_vars),
                                    $alignment_values) `)`
           |`if` `(` $if_expr `)`
+          |`order` `(` custom<ClauseAttr>($order_val) `)`
           |`simdlen` `(` $simdlen  `)`
           |`safelen` `(` $safelen  `)`
     ) `for` custom<LoopControl>($region, $lowerBound, $upperBound, $step,
Index: mlir/test/Dialect/OpenMP/invalid.mlir
===================================================================
--- mlir/test/Dialect/OpenMP/invalid.mlir
+++ mlir/test/Dialect/OpenMP/invalid.mlir
@@ -283,6 +283,16 @@
 
 // -----
 
+func.func @omp_simdloop_order_value(%lb : index, %ub : index, %step : index) {
+  // expected-error @below {{invalid clause value: 'default'}}
+  omp.simdloop order(default) for (%iv): index = (%lb) to (%ub) step (%step) {
+    omp.yield
+  }
+  return
+}
+
+// -----
+
 func.func @omp_simdloop_pretty_simdlen(%lb : index, %ub : index, %step : index) -> () {
   // expected-error @below {{op attribute 'simdlen' failed to satisfy constraint: 64-bit signless integer attribute whose value is positive}}
   omp.simdloop simdlen(0) for (%iv): index = (%lb) to (%ub) step (%step) {
Index: mlir/test/Dialect/OpenMP/ops.mlir
===================================================================
--- mlir/test/Dialect/OpenMP/ops.mlir
+++ mlir/test/Dialect/OpenMP/ops.mlir
@@ -398,6 +398,16 @@
   return
 }
 
+// CHECK-LABEL: omp_simdloop_pretty_order
+func.func @omp_simdloop_pretty_order(%lb : index, %ub : index, %step : index) -> () {
+  // CHECK: omp.simdloop order(concurrent)
+  // CHECK-SAME: for (%{{.*}}) : index = (%{{.*}}) to (%{{.*}}) step (%{{.*}})
+  omp.simdloop order(concurrent) for (%iv): index = (%lb) to (%ub) step (%step) {
+    omp.yield
+  }
+  return
+}
+
 // CHECK-LABEL: omp_simdloop_pretty_simdlen
 func.func @omp_simdloop_pretty_simdlen(%lb : index, %ub : index, %step : index) -> () {
   // CHECK: omp.simdloop simdlen(2) for (%{{.*}}) : index = (%{{.*}}) to (%{{.*}}) step (%{{.*}})