diff --git a/include/string.h b/include/string.h
index 86d1fa4abe..f31a7f6006 100644
--- a/include/string.h
+++ b/include/string.h
@@ -45,6 +45,9 @@ extern void *__memrchr (const void *__s, int __c, size_t __n)
 extern void *__memchr (const void *__s, int __c, size_t __n)
      __attribute_pure__;
 
+extern void __memswap (void *restrict __p1, void *restrict __p2, size_t __n)
+     attribute_hidden;
+
 extern void __bzero (void *__s, size_t __n) __THROW __nonnull ((1));
 
 extern int __ffs (int __i) __attribute__ ((const));
diff --git a/string/Makefile b/string/Makefile
index 8cdfd5b000..3d0a3d5682 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -69,6 +69,7 @@ routines := \
   mempcpy \
   memrchr \
   memset \
+  memswap \
   rawmemchr \
   sigabbrev_np \
   sigdescr_np \
@@ -209,6 +210,18 @@ tests := \
   tst-xbzero-opt \
 # tests
 
+tests-static-internal := \
+  test-memswap \
+# tests-static-internal
+
+tests-internal := \
+  $(tests-static-internal) \
+  # tests-internal
+
+tests-static := \
+  $(tests-static-internal) \
+  # tests-static
+
 # Both tests require the .mo translation files generated by msgfmt.
 tests-translation := \
   tst-strerror \
diff --git a/string/memswap.c b/string/memswap.c
new file mode 100644
index 0000000000..37640c47ad
--- /dev/null
+++ b/string/memswap.c
@@ -0,0 +1,41 @@
+/* Swap the content of two memory blocks, overlap is NOT handled.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+
+void
+__memswap (void *restrict p1, void *restrict p2, size_t n)
+{
+  /* Use multiple small memcpys with constant size to enable inlining on most
+     targets.  */
+  enum { SWAP_GENERIC_SIZE = 32 };
+  unsigned char tmp[SWAP_GENERIC_SIZE];
+  while (n > SWAP_GENERIC_SIZE)
+    {
+      memcpy (tmp, p1, SWAP_GENERIC_SIZE);
+      p1 = __mempcpy (p1, p2, SWAP_GENERIC_SIZE);
+      p2 = __mempcpy (p2, tmp, SWAP_GENERIC_SIZE);
+      n -= SWAP_GENERIC_SIZE;
+    }
+  while (n > 0)
+    {
+      unsigned char t = ((unsigned char *)p1)[--n];
+      ((unsigned char *)p1)[n] = ((unsigned char *)p2)[n];
+      ((unsigned char *)p2)[n] = t;
+    }
+}
diff --git a/string/test-memswap.c b/string/test-memswap.c
new file mode 100644
index 0000000000..7696c43711
--- /dev/null
+++ b/string/test-memswap.c
@@ -0,0 +1,191 @@
+/* Test and measure memcpy functions.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <support/check.h>
+
+#define TEST_MAIN
+#define BUF1PAGES 3
+#include "test-string.h"
+
+static unsigned char *ref1;
+static unsigned char *ref2;
+
+static void
+do_one_test (unsigned char *p1, unsigned char *ref1, unsigned char *p2,
+	     unsigned char *ref2, size_t len)
+{
+  __memswap (p1, p2, len);
+
+  TEST_COMPARE_BLOB (p1, len, ref2, len);
+  TEST_COMPARE_BLOB (p2, len, ref1, len);
+}
+
+static inline void
+do_test (size_t align1, size_t align2, size_t len)
+{
+  align1 &= page_size;
+  if (align1 + len >= page_size)
+    return;
+
+  align2 &= page_size;
+  if (align2 + len >= page_size)
+    return;
+
+  unsigned char *p1 = buf1 + align1;
+  unsigned char *p2 = buf2 + align2;
+  for (size_t repeats = 0; repeats < 2; ++repeats)
+    {
+      size_t i, j;
+      for (i = 0, j = 1; i < len; i++, j += 23)
+	{
+	  ref1[i] = p1[i] = j;
+	  ref2[i] = p2[i] = UCHAR_MAX - j;
+	}
+
+      do_one_test (p1, ref1, p2, ref2, len);
+    }
+}
+
+static void
+do_random_tests (void)
+{
+  for (size_t n = 0; n < ITERATIONS; n++)
+    {
+      size_t len, size, size1, size2, align1, align2;
+
+      if (n == 0)
+        {
+          len = getpagesize ();
+          size = len + 512;
+          size1 = size;
+          size2 = size;
+          align1 = 512;
+          align2 = 512;
+        }
+      else
+        {
+          if ((random () & 255) == 0)
+            size = 65536;
+          else
+            size = 768;
+          if (size > page_size)
+            size = page_size;
+          size1 = size;
+          size2 = size;
+          size_t i = random ();
+          if (i & 3)
+            size -= 256;
+          if (i & 1)
+            size1 -= 256;
+          if (i & 2)
+            size2 -= 256;
+          if (i & 4)
+            {
+              len = random () % size;
+              align1 = size1 - len - (random () & 31);
+              align2 = size2 - len - (random () & 31);
+              if (align1 > size1)
+                align1 = 0;
+              if (align2 > size2)
+                align2 = 0;
+            }
+          else
+            {
+              align1 = random () & 63;
+              align2 = random () & 63;
+              len = random () % size;
+              if (align1 + len > size1)
+                align1 = size1 - len;
+              if (align2 + len > size2)
+                align2 = size2 - len;
+            }
+        }
+      unsigned char *p1 = buf1 + page_size - size1;
+      unsigned char *p2 = buf2 + page_size - size2;
+      size_t j = align1 + len + 256;
+      if (j > size1)
+        j = size1;
+      for (size_t i = 0; i < j; ++i)
+	ref1[i] = p1[i] = random () & 255;
+
+      j = align2 + len + 256;
+      if (j > size2)
+	j = size2;
+
+      for (size_t i = 0; i < j; ++i)
+	ref2[i] = p2[i] = random () & 255;
+
+      do_one_test (p1 + align1, ref1 + align1, p2 + align2, ref2 + align2, len);
+    }
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+  /* Use the start of buf1 for reference buffers.  */
+  ref1 = buf1;
+  ref2 = buf1 + page_size;
+  buf1 = ref2 + page_size;
+
+  printf ("%23s", "");
+  printf ("\t__memswap\n");
+
+  for (size_t i = 0; i < 18; ++i)
+    {
+      do_test (0, 0, 1 << i);
+      do_test (i, 0, 1 << i);
+      do_test (0, i, 1 << i);
+      do_test (i, i, 1 << i);
+    }
+
+  for (size_t i = 0; i < 32; ++i)
+    {
+      do_test (0, 0, i);
+      do_test (i, 0, i);
+      do_test (0, i, i);
+      do_test (i, i, i);
+    }
+
+  for (size_t i = 3; i < 32; ++i)
+    {
+      if ((i & (i - 1)) == 0)
+        continue;
+      do_test (0, 0, 16 * i);
+      do_test (i, 0, 16 * i);
+      do_test (0, i, 16 * i);
+      do_test (i, i, 16 * i);
+    }
+
+  for (size_t i = 19; i <= 25; ++i)
+    {
+      do_test (255, 0, 1 << i);
+      do_test (0, 4000, 1 << i);
+      do_test (0, 255, i);
+      do_test (0, 4000, i);
+    }
+
+  do_test (0, 0, getpagesize ());
+
+  do_random_tests ();
+
+  return 0;
+}
+
+#include <support/test-driver.c>
