auto import from //depot/cupcake/@135843
diff --git a/libc/string/memmem.c b/libc/string/memmem.c
new file mode 100644
index 0000000..e72501b
--- /dev/null
+++ b/libc/string/memmem.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * 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.
+ *
+ * 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.
+ */
+/*
+ * This uses the "Not So Naive" algorithm, a very simple but
+ * usually effective algorithm, see:
+ * http://www-igm.univ-mlv.fr/~lecroq/string/
+ */
+#include <string.h>
+
+void *memmem(const void *haystack, size_t n, const void *needle, size_t m)
+{
+ if (m > n || !m || !n)
+ return NULL;
+
+ if (__builtin_expect((m > 1), 1)) {
+ const unsigned char* y = (const unsigned char*) haystack;
+ const unsigned char* x = (const unsigned char*) needle;
+ size_t j = 0;
+ size_t k = 1, l = 2;
+
+ if (x[0] == x[1]) {
+ k = 2;
+ l = 1;
+ }
+ while (j <= n-m) {
+ if (x[1] != y[j+1]) {
+ j += k;
+ } else {
+ if (!memcmp(x+2, y+j+2, m-2) && x[0] == y[j])
+ return (void*) &y[j];
+ j += l;
+ }
+ }
+ } else {
+ /* degenerate case */
+ return memchr(haystack, ((unsigned char*)needle)[0], n);
+ }
+ return NULL;
+}