diff --git a/libc/bionic/wcwidth.cpp b/libc/bionic/wcwidth.cpp
new file mode 100644
index 0000000..9676b5a
--- /dev/null
+++ b/libc/bionic/wcwidth.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2017 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 <wchar.h>
+
+#include "private/icu.h"
+
+int wcwidth(wchar_t wc) {
+  // Fast-path ASCII.
+  if (wc >= 0x20 && wc < 0x7f) return 1;
+
+  // ASCII NUL is a special case.
+  if (wc == 0) return 0;
+
+  // C0.
+  if (wc < ' ' || (wc >= 0x7f && wc <= 0xa0)) return -1;
+
+  // Now for the i18n part. This isn't defined or standardized, so a lot of the choices are
+  // pretty arbitrary. See https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c for more details.
+
+  // Fancy unicode control characters?
+  switch (__icu_charType(wc)) {
+   case -1:
+    // No icu4c available; give up.
+    return -1;
+   case U_CONTROL_CHAR:
+    return -1;
+   case U_NON_SPACING_MARK:
+   case U_ENCLOSING_MARK:
+   case U_FORMAT_CHAR:
+    return 0;
+  }
+  if (__icu_hasBinaryProperty(wc, UCHAR_DEFAULT_IGNORABLE_CODE_POINT, nullptr)) return 0;
+
+  // Medial and final jamo render as zero width when used correctly.
+  switch (__icu_getIntPropertyValue(wc, UCHAR_HANGUL_SYLLABLE_TYPE)) {
+   case U_HST_VOWEL_JAMO:
+   case U_HST_TRAILING_JAMO:
+    return 0;
+   case U_HST_LEADING_JAMO:
+   case U_HST_LV_SYLLABLE:
+   case U_HST_LVT_SYLLABLE:
+    return 2;
+  }
+
+  if (wc >= 0x3248 && wc <= 0x4dff) {
+    // Circled two-digit CJK "speed sign" numbers. EastAsianWidth is ambiguous,
+    // but wide makes more sense.
+    if (wc <= 0x324f) return 2;
+    // Hexagrams. EastAsianWidth is neutral, but wide seems better.
+    if (wc >= 0x4dc0) return 2;
+  }
+
+  // The EastAsianWidth property is at least defined by the Unicode standard!
+  switch (__icu_getIntPropertyValue(wc, UCHAR_EAST_ASIAN_WIDTH)) {
+   case U_EA_AMBIGUOUS:
+   case U_EA_HALFWIDTH:
+   case U_EA_NARROW:
+   case U_EA_NEUTRAL:
+    return 1;
+   case U_EA_FULLWIDTH:
+   case U_EA_WIDE:
+    return 2;
+  }
+
+  return 0;
+}