diff --git a/libc/arch-mips/string/strlen.c b/libc/arch-mips/string/strlen.c
index 488e3c8..491efae 100644
--- a/libc/arch-mips/string/strlen.c
+++ b/libc/arch-mips/string/strlen.c
@@ -1,43 +1,115 @@
-/*	$OpenBSD: strlen.c,v 1.8 2014/06/10 04:17:37 deraadt Exp $	*/
-
-/*-
- * Copyright (c) 1990, 1993
- *	The Regents of the University of California.  All rights reserved.
+/*
+ * Copyright (c) 2017 Imagination Technologies.
+ *
+ * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. 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.
- * 3. Neither the name of the University 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 REGENTS 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 REGENTS 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.
+ *      * 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 Imagination Technologies 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>
 
-size_t
-strlen(const char *str) __overloadable
-{
-	const char *s;
+#define op_t        unsigned long int
+#define op_size     sizeof (op_t)
 
-	for (s = str; *s; ++s)
-		;
-	return (s - str);
+#if __mips64 || __mips_isa_rev >= 2
+static inline size_t __attribute__ ((always_inline))
+do_bytes (const char *base, const char *p, op_t inval)
+{
+  op_t outval = 0;
+#if __mips64
+  __asm__ volatile (
+    "dsbh %1, %0 \n\t"
+    "dshd %0, %1 \n\t"
+    "dclz %1, %0 \n\t"
+    : "+r" (inval), "+r" (outval)
+  );
+#else
+  __asm__ volatile (
+    "wsbh %1, %0 \n\t"
+    "rotr %0, %1, 16 \n\t"
+    "clz %1, %0 \n\t"
+    : "+r" (inval), "+r" (outval)
+  );
+#endif
+  p += (outval >> 3);
+  return (size_t) (p - base);
 }
 
+#define DO_WORD(w, cnt) {                                \
+  op_t val = ((w[cnt] - mask_1) & ~w[cnt]) & mask_128;   \
+  if (val)                                               \
+    return do_bytes(str, (const char *)(w + cnt), val);  \
+}
+#else
+static inline size_t __attribute__ ((always_inline))
+do_bytes (const char *base, const char *p)
+{
+  for (; *p; ++p);
+  return (size_t) (p - base);
+}
+
+#define DO_WORD(w, cnt) {                           \
+  if (((w[cnt] - mask_1) & ~w[cnt]) & mask_128)     \
+    return do_bytes(str, (const char *)(w + cnt));  \
+}
+#endif
+
+size_t
+strlen (const char *str) __overloadable
+{
+  if (*str) {
+    const char *p = (const char *) str;
+    const op_t *w;
+    op_t mask_1, mask_128;
+
+    while ((size_t) p % sizeof (op_t)) {
+      if (!(*p))
+        return (p - str);
+      p++;
+    }
+
+    __asm__ volatile (
+      "li %0, 0x01010101 \n\t"
+      : "=r" (mask_1)
+    );
+#if __mips64
+    mask_1 |= mask_1 << 32;
+#endif
+    mask_128 = mask_1 << 7;
+
+    w = (const op_t *) p;
+
+    while (1) {
+      DO_WORD(w, 0);
+      DO_WORD(w, 1);
+      DO_WORD(w, 2);
+      DO_WORD(w, 3);
+      w += 4;
+    }
+  }
+  return 0;
+}