diff --git a/libc/private/icu4x.h b/libc/private/icu4x.h
new file mode 100644
index 0000000..8b7e1d0
--- /dev/null
+++ b/libc/private/icu4x.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#pragma once
+
+#include <ctype.h>
+#include <stdint.h>
+#include <wchar.h>
+
+enum UCharCategory {
+  U_NON_SPACING_MARK = 6,
+  U_ENCLOSING_MARK = 7,
+  U_DECIMAL_NUMBER = 9,
+  U_CONTROL_CHAR = 15,
+  U_FORMAT_CHAR = 16,
+  U_DASH_PUNCTUATION = 19,
+  U_OTHER_PUNCTUATION = 23,
+};
+
+enum UEastAsianWidth {
+  U_EA_NEUTRAL,
+  U_EA_AMBIGUOUS,
+  U_EA_HALFWIDTH,
+  U_EA_FULLWIDTH,
+  U_EA_NARROW,
+  U_EA_WIDE,
+};
+
+enum UHangulSyllableType {
+  U_HST_NOT_APPLICABLE,
+  U_HST_LEADING_JAMO,
+  U_HST_VOWEL_JAMO,
+  U_HST_TRAILING_JAMO,
+  U_HST_LV_SYLLABLE,
+  U_HST_LVT_SYLLABLE,
+};
+
+__BEGIN_DECLS
+
+uint8_t __icu4x_bionic_general_category(uint32_t cp);
+uint8_t __icu4x_bionic_east_asian_width(uint32_t cp);
+uint8_t __icu4x_bionic_hangul_syllable_type(uint32_t cp);
+
+bool __icu4x_bionic_is_alphabetic(uint32_t cp);
+bool __icu4x_bionic_is_default_ignorable_code_point(uint32_t cp);
+bool __icu4x_bionic_is_lowercase(uint32_t cp);
+bool __icu4x_bionic_is_alnum(uint32_t cp);
+bool __icu4x_bionic_is_blank(uint32_t cp);
+bool __icu4x_bionic_is_graph(uint32_t cp);
+bool __icu4x_bionic_is_print(uint32_t cp);
+bool __icu4x_bionic_is_xdigit(uint32_t cp);
+bool __icu4x_bionic_is_white_space(uint32_t cp);
+bool __icu4x_bionic_is_uppercase(uint32_t cp);
+
+uint32_t __icu4x_bionic_to_upper(uint32_t ch);
+uint32_t __icu4x_bionic_to_lower(uint32_t ch);
+
+__END_DECLS