diff --git a/libc/bionic/mbrtoc32.cpp b/libc/bionic/mbrtoc32.cpp
new file mode 100644
index 0000000..bd40ecf
--- /dev/null
+++ b/libc/bionic/mbrtoc32.cpp
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include <errno.h>
+#include <sys/param.h>
+#include <uchar.h>
+#include <wchar.h>
+
+#include "private/bionic_mbstate.h"
+
+size_t mbrtoc32(char32_t* pc32, const char* s, size_t n, mbstate_t* ps) {
+  static mbstate_t __private_state;
+  mbstate_t* state = (ps == NULL) ? &__private_state : ps;
+
+  // We should never get to a state which has all 4 bytes of the sequence set.
+  // Full state verification is done when decoding the sequence (after we have
+  // all the bytes).
+  if (mbstate_get_byte(state, 3) != 0) {
+    return reset_and_return_illegal(EINVAL, state);
+  }
+
+  if (s == NULL) {
+    s = "";
+    n = 1;
+    pc32 = NULL;
+  }
+
+  if (n == 0) {
+    return 0;
+  }
+
+  uint8_t ch;
+  if (mbsinit(state) && (((ch = static_cast<uint8_t>(*s)) & ~0x7f) == 0)) {
+    // Fast path for plain ASCII characters.
+    if (pc32 != NULL) {
+      *pc32 = ch;
+    }
+    return (ch != '\0' ? 1 : 0);
+  }
+
+  // Determine the number of octets that make up this character
+  // from the first octet, and a mask that extracts the
+  // interesting bits of the first octet. We already know
+  // the character is at least two bytes long.
+  size_t length;
+  int mask;
+
+  // We also specify a lower bound for the character code to
+  // detect redundant, non-"shortest form" encodings. For
+  // example, the sequence C0 80 is _not_ a legal representation
+  // of the null character. This enforces a 1-to-1 mapping
+  // between character codes and their multibyte representations.
+  char32_t lower_bound;
+
+  // The first byte in the state (if any) tells the length.
+  size_t bytes_so_far = mbstate_bytes_so_far(state);
+  ch = bytes_so_far > 0 ? mbstate_get_byte(state, 0) : static_cast<uint8_t>(*s);
+  if ((ch & 0x80) == 0) {
+    mask = 0x7f;
+    length = 1;
+    lower_bound = 0;
+  } else if ((ch & 0xe0) == 0xc0) {
+    mask = 0x1f;
+    length = 2;
+    lower_bound = 0x80;
+  } else if ((ch & 0xf0) == 0xe0) {
+    mask = 0x0f;
+    length = 3;
+    lower_bound = 0x800;
+  } else if ((ch & 0xf8) == 0xf0) {
+    mask = 0x07;
+    length = 4;
+    lower_bound = 0x10000;
+  } else {
+    // Malformed input; input is not UTF-8. See RFC 3629.
+    return reset_and_return_illegal(EILSEQ, state);
+  }
+
+  // Fill in the state.
+  size_t bytes_wanted = length - bytes_so_far;
+  size_t i;
+  for (i = 0; i < MIN(bytes_wanted, n); i++) {
+    if (!mbsinit(state) && ((*s & 0xc0) != 0x80)) {
+      // Malformed input; bad characters in the middle of a character.
+      return reset_and_return_illegal(EILSEQ, state);
+    }
+    mbstate_set_byte(state, bytes_so_far + i, *s++);
+  }
+  if (i < bytes_wanted) {
+    return __MB_ERR_INCOMPLETE_SEQUENCE;
+  }
+
+  // Decode the octet sequence representing the character in chunks
+  // of 6 bits, most significant first.
+  char32_t c32 = mbstate_get_byte(state, 0) & mask;
+  for (i = 1; i < length; i++) {
+    c32 <<= 6;
+    c32 |= mbstate_get_byte(state, i) & 0x3f;
+  }
+
+  if (c32 < lower_bound) {
+    // Malformed input; redundant encoding.
+    return reset_and_return_illegal(EILSEQ, state);
+  }
+  if ((c32 >= 0xd800 && c32 <= 0xdfff) || c32 == 0xfffe || c32 == 0xffff) {
+    // Malformed input; invalid code points.
+    return reset_and_return_illegal(EILSEQ, state);
+  }
+  if (pc32 != NULL) {
+    *pc32 = c32;
+  }
+  return reset_and_return(c32 == U'\0' ? 0 : bytes_wanted, state);
+}