diff --git a/libcxx/include/__algorithm/pstl_backends/cpu_backend.h b/libcxx/include/__algorithm/pstl_backends/cpu_backend.h
--- a/libcxx/include/__algorithm/pstl_backends/cpu_backend.h
+++ b/libcxx/include/__algorithm/pstl_backends/cpu_backend.h
@@ -27,6 +27,7 @@
 #include <__algorithm/pstl_backends/cpu_backends/fill.h>
 #include <__algorithm/pstl_backends/cpu_backends/find_if.h>
 #include <__algorithm/pstl_backends/cpu_backends/for_each.h>
+#include <__algorithm/pstl_backends/cpu_backends/merge.h>
 #include <__algorithm/pstl_backends/cpu_backends/transform.h>
 
 #endif // _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKEND_H
diff --git a/libcxx/include/__algorithm/pstl_backends/cpu_backends/merge.h b/libcxx/include/__algorithm/pstl_backends/cpu_backends/merge.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/pstl_backends/cpu_backends/merge.h
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
+#define _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
+
+#include <__algorithm/pstl_backends/cpu_backends/backend.h>
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _ForwatdOutIterator,
+          class _Comp>
+_LIBCPP_HIDE_FROM_ABI _ForwatdOutIterator __pstl_merge(
+    __cpu_backend_tag,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _ForwatdOutIterator __result) {
+
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
diff --git a/libcxx/include/__algorithm/pstl_backends/cpu_backends/serial.h b/libcxx/include/__algorithm/pstl_backends/cpu_backends/serial.h
--- a/libcxx/include/__algorithm/pstl_backends/cpu_backends/serial.h
+++ b/libcxx/include/__algorithm/pstl_backends/cpu_backends/serial.h
@@ -30,6 +30,22 @@
 
 _LIBCPP_HIDE_FROM_ABI inline void __cancel_execution() {}
 
+template <class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _Compare,
+          class _LeafMerge>
+_LIBCPP_HIDE_FROM_ABI void __parallel_merge(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __outit,
+    _Compare __comp,
+    _LeafMerge __leaf_merge) {
+  __leaf_merge(__first1, __last1, __first2, __last2, __outit, __comp);
+}
+
 // TODO: Complete this list
 
 } // namespace __serial_cpu_backend
diff --git a/libcxx/include/__algorithm/pstl_merge.h b/libcxx/include/__algorithm/pstl_merge.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/pstl_merge.h
@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PSTL_MERGE_H
+#define _LIBCPP___ALGORITHM_PSTL_MERGE_H
+
+#include <__algorithm/pstl_backend.h>
+#include <__config>
+#include <__type_traits/is_execution_policy.h>
+#include <__type_traits/remove_cvref.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _ForwardOutIterator,
+          class _Comp,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_ForwardOutIterator
+merge(_ExecutionPolicy&& __policy,
+      _ForwardIterator1 __first1,
+      _ForwardIterator1 __last1,
+      _ForwardIterator2 __first2,
+      _ForwardIterator2 __last2,
+      _ForwardOutIterator __result,
+      _Comp __comp) {
+  using _Backend = typename __select_backend<_ExecutionPolicy>::type;
+  std::__pstl_merge<_RawPolicy>(
+      _Backend{},
+      std::move(__first1),
+      std::move(__last1),
+      std::move(__first2),
+      std::move(__last2),
+      std::move(__result));
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
+
+#endif // _LIBCPP___ALGORITHM_PSTL_MERGE_H
diff --git a/libcxx/include/__pstl/internal/parallel_backend_serial.h b/libcxx/include/__pstl/internal/parallel_backend_serial.h
--- a/libcxx/include/__pstl/internal/parallel_backend_serial.h
+++ b/libcxx/include/__pstl/internal/parallel_backend_serial.h
@@ -98,16 +98,6 @@
     __leaf_sort(__first, __last, __comp);
 }
 
-template <class _ExecutionPolicy, typename _RandomAccessIterator1, typename _RandomAccessIterator2,
-          typename _RandomAccessIterator3, typename _Compare, typename _LeafMerge>
-_LIBCPP_HIDE_FROM_ABI void
-__parallel_merge(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator1 __first1,
-                 _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2,
-                 _RandomAccessIterator3 __outit, _Compare __comp, _LeafMerge __leaf_merge)
-{
-    __leaf_merge(__first1, __last1, __first2, __last2, __outit, __comp);
-}
-
 template <class _ExecutionPolicy, typename _F1, typename _F2>
 _LIBCPP_HIDE_FROM_ABI void
 __parallel_invoke(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _F1&& __f1, _F2&& __f2)