diff --git a/libc/arch-mips64/string/mips_strlen.c b/libc/arch-mips64/string/mips_strlen.c
new file mode 100644
index 0000000..37e5865
--- /dev/null
+++ b/libc/arch-mips64/string/mips_strlen.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2010 MIPS Technologies, Inc.
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *      * Redistributions of source code must retain the above copyright
+ *        notice, this list of conditions and the following disclaimer.
+ *      * Redistributions in binary form must reproduce the above copyright
+ *        notice, this list of conditions and the following disclaimer
+ *        in the documentation and/or other materials provided with
+ *        the distribution.
+ *      * Neither the name of MIPS Technologies Inc. nor the names of its
+ *        contributors may be used to endorse or promote products derived
+ *        from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <string.h>
+#include "mips-string-ops.h"
+
+#define do_strlen_word(__av) {\
+    if (detect_zero(x,x,_01s,_80s)) break;\
+    x = __av;\
+    cnt += sizeof (unsigned);\
+    }
+
+#define do_strlen_byte(__x) {\
+  if ((bx.b.B##__x) == 0) break;\
+  ++cnt;\
+  }
+
+#if SMOKE_TEST_MIPS_STRLEN
+#define strlen my_strlen
+#endif
+
+size_t
+strlen (const char *_a)
+{
+  int cnt = 0;
+  unsigned long x;
+
+  /* align the string to word boundary so we can do word at a time.  */
+  if ((cvt_ptr_to (unsigned long, _a) & (sizeof (unsigned long) - 1)) != 0)
+    {
+      if ((cvt_ptr_to (unsigned long, _a) & 1) != 0)
+	{
+	  if (get_byte (_a, 0) == 0)
+	    return cnt;
+	  /* set bit 1 so 2-bytes are checked and incremented. */
+	  inc_ptr_as (char *, _a, 1);
+	  ++cnt;
+	}
+      if ((cvt_ptr_to (unsigned long, _a) & 2) != 0)
+	{
+	  if (get_byte (_a, 0) == 0)
+	    return cnt + 0;
+	  if (get_byte (_a, 1) == 0)
+	    return cnt + 1;
+	  inc_ptr_as (char *, _a, 2);
+	  cnt += 2;
+	}
+    }
+
+#if __mips64
+#error strlen: mips64 check for 4-byte alignment not implemented.
+#endif
+
+  if (1)
+    {
+      def_and_set_01 (_01s);
+      def_and_set_80 (_80s);
+
+      /* as advantagous as it is to performance, this code cannot pre-load
+         the following word, nor can it prefetch the next line at the start
+         of the loop since the string can be at the end of a page with the
+         following page unmapped. There are tests in the suite to catch
+         any attempt to go beyond the current word. */
+      x = get_word (_a, 0);
+      while (1)
+	{
+	  /* doing 8 words should cover most strings.  */
+	  do_strlen_word (get_word (_a, 1));
+	  do_strlen_word (get_word (_a, 2));
+	  do_strlen_word (get_word (_a, 3));
+	  do_strlen_word (get_word (_a, 4));
+	  do_strlen_word (get_word (_a, 5));
+	  do_strlen_word (get_word (_a, 6));
+	  do_strlen_word (get_word (_a, 7));
+	  do_strlen_word (get_word (_a, 8));
+	  inc_ptr_as (unsigned long*, _a, 8);
+	}
+    }
+  while (1)
+    {
+      /* pull apart the last word processed and find the zero.  */
+      bitfields_t bx;
+      bx.v = x;
+#if __mips64
+      do_strlen_byte (0);
+      do_strlen_byte (1);
+      do_strlen_byte (2);
+      do_strlen_byte (3);
+      do_strlen_byte (4);
+      do_strlen_byte (5);
+      do_strlen_byte (6);
+#else
+      do_strlen_byte (0);
+      do_strlen_byte (1);
+      do_strlen_byte (2);
+#endif
+      /* last byte is zero */
+      break;
+    }
+  return cnt;
+}
+
+#undef do_strlen_byte
+#undef do_strlen_word
+
+#if SMOKE_TEST_MIPS_STRLEN
+#include <stdio.h>
+char str1[] = "DHRYSTONE PROGRAM, 1'ST STRING";
+char str2[] = "DHRYSTONE PROGRAM, 2'ST STRING";
+
+char str3[] = "another string";
+char str4[] = "another";
+
+char str5[] = "somes tring";
+char str6[] = "somes_tring";
+
+char str7[16], str8[16];
+
+static char *
+chk (unsigned long mine, unsigned long libs, int *errors)
+{
+  static char answer[1024];
+  char *result = mine == libs ? "PASS" : "FAIL";
+  sprintf (answer, "new_strlen=%d: lib_strlen=%d: %s!", mine, libs, result);
+  if (mine != libs)
+    (*errors)++;
+  return answer;
+}
+
+int
+main (int argc, char **argv)
+{
+  int errors = 0;
+  /* set -1 in one position */
+  str6[5] = 0xff;
+  /* set zero in same position with junk in following 3 */
+  str7[0] = str8[0] = 0;
+  str7[1] = 0xff;
+  str7[2] = 'a';
+  str7[3] = 2;
+  str8[1] = 's';
+  str8[2] = -2;
+  str8[3] = 0;
+
+  fprintf (stderr, "========== mips_strlen%s test...\n",
+	   argv[0] ? argv[0] : "unknown strlen");
+#define P(__x,__y) {\
+    int a = my_strlen(__x + __y);\
+    int b = (strlen)(__x + __y) /* library version */;\
+    fprintf(stderr,"%s+%d: %s\n",#__x,__y,chk(a,b,&errors));\
+    }
+
+  P (str1, 0);
+  P (str1, 1);
+  P (str1, 2);
+  P (str1, 3);
+
+  P (str2, 0);
+  P (str2, 1);
+  P (str2, 2);
+  P (str2, 3);
+
+  P (str3, 0);
+  P (str3, 1);
+  P (str3, 2);
+  P (str3, 3);
+
+  P (str4, 0);
+  P (str4, 1);
+  P (str4, 2);
+  P (str4, 3);
+
+  P (str5, 0);
+  P (str5, 1);
+  P (str5, 2);
+  P (str5, 3);
+
+  P (str6, 0);
+  P (str6, 1);
+  P (str6, 2);
+  P (str6, 3);
+
+  P (str7, 0);
+  P (str7, 1);
+  P (str7, 2);
+  P (str7, 3);
+
+  P (str8, 0);
+  P (str8, 1);
+  P (str8, 2);
+  P (str8, 3);
+
+  return errors;
+}
+#endif