diff --git a/Makefile.am b/Makefile.am
index ed56a9c..1a4c0c0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,7 +44,8 @@ check_PROGRAMS = \
 	tests/test-strcmp \
 	tests/test-strcpy \
 	tests/test-strlen \
-	tests/test-strncmp
+	tests/test-strncmp \
+	tests/test-strnlen
 
 # Options for the tests
 tests_cflags = -I$(srcdir)/tests $(AM_CFLAGS)
diff --git a/tests/test-strnlen.c b/tests/test-strnlen.c
new file mode 100644
index 0000000..7c9a45a
--- /dev/null
+++ b/tests/test-strnlen.c
@@ -0,0 +1,199 @@
+/* Test and measure strlen functions.
+   Copyright (C) 1999-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written by Jakub Jelinek <jakub@redhat.com>, 1999.
+
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+#define TEST_MAIN
+#define TEST_NAME "strnlen"
+#include "test-string.h"
+
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+
+typedef size_t (*proto_t) (const char *, size_t);
+size_t simple_strnlen (const char *, size_t);
+
+IMPL (simple_strnlen, 0)
+IMPL (strnlen, 1)
+
+size_t
+simple_strnlen (const char *s, size_t maxlen)
+{
+  size_t i;
+
+  for (i = 0; i < maxlen && s[i]; ++i);
+  return i;
+}
+
+static void
+do_one_test (impl_t *impl, const char *s, size_t maxlen, size_t exp_len)
+{
+  size_t len = CALL (impl, s, maxlen);
+  if (len != exp_len)
+    {
+      error (0, 0, "Wrong result in function %s %zd %zd", impl->name,
+	     len, exp_len);
+      ret = 1;
+      return;
+    }
+
+  if (HP_TIMING_AVAIL)
+    {
+      hp_timing_t start __attribute ((unused));
+      hp_timing_t stop __attribute ((unused));
+      hp_timing_t best_time = ~ (hp_timing_t) 0;
+      size_t i;
+
+      for (i = 0; i < 32; ++i)
+	{
+	  HP_TIMING_NOW (start);
+	  CALL (impl, s, maxlen);
+	  HP_TIMING_NOW (stop);
+	  HP_TIMING_BEST (best_time, start, stop);
+	}
+
+      printf ("\t%zd", (size_t) best_time);
+    }
+}
+
+static void
+do_test (size_t align, size_t len, size_t maxlen, int max_char)
+{
+  size_t i;
+
+  align &= 7;
+  if (align + len >= page_size)
+    return;
+
+  for (i = 0; i < len; ++i)
+    buf1[align + i] = 1 + 7 * i % max_char;
+  buf1[align + len] = 0;
+
+  if (HP_TIMING_AVAIL)
+    printf ("Length %4zd, alignment %2zd:", len, align);
+
+  FOR_EACH_IMPL (impl, 0)
+    do_one_test (impl, (char *) (buf1 + align), maxlen, MIN (len, maxlen));
+
+  if (HP_TIMING_AVAIL)
+    putchar ('\n');
+}
+
+static void
+do_random_tests (void)
+{
+  size_t i, j, n, align, len;
+  unsigned char *p = buf1 + page_size - 512;
+
+  for (n = 0; n < ITERATIONS; n++)
+    {
+      align = random () & 15;
+      len = random () & 511;
+      if (len + align > 510)
+	len = 511 - align - (random () & 7);
+      j = len + align + 64;
+      if (j > 512)
+	j = 512;
+
+      for (i = 0; i < j; i++)
+	{
+	  if (i == len + align)
+	    p[i] = 0;
+	  else
+	    {
+	      p[i] = random () & 255;
+	      if (i >= align && i < len + align && !p[i])
+		p[i] = (random () & 127) + 1;
+	    }
+	}
+
+      FOR_EACH_IMPL (impl, 1)
+	{
+	  if (len > 0
+	      && CALL (impl, (char *) (p + align), len - 1) != len - 1)
+	    {
+	      error (0, 0, "Iteration %zd (limited) - wrong result in function %s (%zd) %zd != %zd, p %p",
+		     n, impl->name, align,
+		     CALL (impl, (char *) (p + align), len - 1), len - 1, p);
+	      ret = 1;
+	    }
+	  if (CALL (impl, (char *) (p + align), len) != len)
+	    {
+	      error (0, 0, "Iteration %zd (exact) - wrong result in function %s (%zd) %zd != %zd, p %p",
+		     n, impl->name, align,
+		     CALL (impl, (char *) (p + align), len), len, p);
+	      ret = 1;
+	    }
+	  if (CALL (impl, (char *) (p + align), len + 1) != len)
+	    {
+	      error (0, 0, "Iteration %zd (long) - wrong result in function %s (%zd) %zd != %zd, p %p",
+		     n, impl->name, align,
+		     CALL (impl, (char *) (p + align), len + 1), len, p);
+	      ret = 1;
+	    }
+	}
+    }
+}
+
+int
+test_main (void)
+{
+  size_t i;
+
+  test_init ();
+
+  printf ("%20s", "");
+  FOR_EACH_IMPL (impl, 0)
+    printf ("\t%s", impl->name);
+  putchar ('\n');
+
+  for (i = 1; i < 8; ++i)
+    {
+      do_test (0, i, i - 1, 127);
+      do_test (0, i, i, 127);
+      do_test (0, i, i + 1, 127);
+    }
+
+  for (i = 1; i < 8; ++i)
+    {
+      do_test (i, i, i - 1, 127);
+      do_test (i, i, i, 127);
+      do_test (i, i, i + 1, 127);
+    }
+
+  for (i = 2; i <= 10; ++i)
+    {
+      do_test (0, 1 << i, 5000, 127);
+      do_test (1, 1 << i, 5000, 127);
+    }
+
+  for (i = 1; i < 8; ++i)
+    do_test (0, i, 5000, 255);
+
+  for (i = 1; i < 8; ++i)
+    do_test (i, i, 5000, 255);
+
+  for (i = 2; i <= 10; ++i)
+    {
+      do_test (0, 1 << i, 5000, 255);
+      do_test (1, 1 << i, 5000, 255);
+    }
+
+  do_random_tests ();
+  return ret;
+}
+
+#include "test-skeleton.c"
-- 
1.7.9.5

