diff --git a/libc/bionic/ctype.cpp b/libc/bionic/ctype.cpp
index 2b31d52..b72935b 100644
--- a/libc/bionic/ctype.cpp
+++ b/libc/bionic/ctype.cpp
@@ -83,3 +83,15 @@
 int tolower_l(int c, locale_t) {
   return tolower(c);
 }
+
+int tolower(int c) {
+  if (c >= 'A' && c <= 'Z') return c | 0x20;
+  return c;
+}
+
+int toupper(int c) {
+  // Using EOR rather than AND makes no difference on arm, but saves an
+  // instruction on arm64.
+  if (c >= 'a' && c <= 'z') return c ^ 0x20;
+  return c;
+}
diff --git a/libc/bionic/ndk_cruft_data.cpp b/libc/bionic/ndk_cruft_data.cpp
new file mode 100644
index 0000000..e512b4a
--- /dev/null
+++ b/libc/bionic/ndk_cruft_data.cpp
@@ -0,0 +1,94 @@
+
+// Ancient NDKs' <ctype.h> contained inline references to these tables.
+
+#if !defined(__LP64__)
+
+/*	$OpenBSD: tolower_.c,v 1.11 2015/09/19 04:02:21 guenther Exp $ */
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+static const short _C_tolower_[] = {
+	-1,
+	0x00,	0x01,	0x02,	0x03,	0x04,	0x05,	0x06,	0x07,
+	0x08,	0x09,	0x0a,	0x0b,	0x0c,	0x0d,	0x0e,	0x0f,
+	0x10,	0x11,	0x12,	0x13,	0x14,	0x15,	0x16,	0x17,
+	0x18,	0x19,	0x1a,	0x1b,	0x1c,	0x1d,	0x1e,	0x1f,
+	0x20,	0x21,	0x22,	0x23,	0x24,	0x25,	0x26,	0x27,
+	0x28,	0x29,	0x2a,	0x2b,	0x2c,	0x2d,	0x2e,	0x2f,
+	0x30,	0x31,	0x32,	0x33,	0x34,	0x35,	0x36,	0x37,
+	0x38,	0x39,	0x3a,	0x3b,	0x3c,	0x3d,	0x3e,	0x3f,
+	0x40,	'a',	'b',	'c',	'd',	'e',	'f',	'g',
+	'h',	'i',	'j',	'k',	'l',	'm',	'n',	'o',
+	'p',	'q',	'r',	's',	't',	'u',	'v',	'w',
+	'x',	'y',	'z',	0x5b,	0x5c,	0x5d,	0x5e,	0x5f,
+	0x60,	0x61,	0x62,	0x63,	0x64,	0x65,	0x66,	0x67,
+	0x68,	0x69,	0x6a,	0x6b,	0x6c,	0x6d,	0x6e,	0x6f,
+	0x70,	0x71,	0x72,	0x73,	0x74,	0x75,	0x76,	0x77,
+	0x78,	0x79,	0x7a,	0x7b,	0x7c,	0x7d,	0x7e,	0x7f,
+	0x80,	0x81,	0x82,	0x83,	0x84,	0x85,	0x86,	0x87,
+	0x88,	0x89,	0x8a,	0x8b,	0x8c,	0x8d,	0x8e,	0x8f,
+	0x90,	0x91,	0x92,	0x93,	0x94,	0x95,	0x96,	0x97,
+	0x98,	0x99,	0x9a,	0x9b,	0x9c,	0x9d,	0x9e,	0x9f,
+	0xa0,	0xa1,	0xa2,	0xa3,	0xa4,	0xa5,	0xa6,	0xa7,
+	0xa8,	0xa9,	0xaa,	0xab,	0xac,	0xad,	0xae,	0xaf,
+	0xb0,	0xb1,	0xb2,	0xb3,	0xb4,	0xb5,	0xb6,	0xb7,
+	0xb8,	0xb9,	0xba,	0xbb,	0xbc,	0xbd,	0xbe,	0xbf,
+	0xc0,	0xc1,	0xc2,	0xc3,	0xc4,	0xc5,	0xc6,	0xc7,
+	0xc8,	0xc9,	0xca,	0xcb,	0xcc,	0xcd,	0xce,	0xcf,
+	0xd0,	0xd1,	0xd2,	0xd3,	0xd4,	0xd5,	0xd6,	0xd7,
+	0xd8,	0xd9,	0xda,	0xdb,	0xdc,	0xdd,	0xde,	0xdf,
+	0xe0,	0xe1,	0xe2,	0xe3,	0xe4,	0xe5,	0xe6,	0xe7,
+	0xe8,	0xe9,	0xea,	0xeb,	0xec,	0xed,	0xee,	0xef,
+	0xf0,	0xf1,	0xf2,	0xf3,	0xf4,	0xf5,	0xf6,	0xf7,
+	0xf8,	0xf9,	0xfa,	0xfb,	0xfc,	0xfd,	0xfe,	0xff
+};
+
+const short *_tolower_tab_ = _C_tolower_;
+
+/*	$OpenBSD: toupper_.c,v 1.12 2015/09/19 04:02:21 guenther Exp $ */
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+static const short _C_toupper_[] = {
+	-1,
+	0x00,	0x01,	0x02,	0x03,	0x04,	0x05,	0x06,	0x07,
+	0x08,	0x09,	0x0a,	0x0b,	0x0c,	0x0d,	0x0e,	0x0f,
+	0x10,	0x11,	0x12,	0x13,	0x14,	0x15,	0x16,	0x17,
+	0x18,	0x19,	0x1a,	0x1b,	0x1c,	0x1d,	0x1e,	0x1f,
+	0x20,	0x21,	0x22,	0x23,	0x24,	0x25,	0x26,	0x27,
+	0x28,	0x29,	0x2a,	0x2b,	0x2c,	0x2d,	0x2e,	0x2f,
+	0x30,	0x31,	0x32,	0x33,	0x34,	0x35,	0x36,	0x37,
+	0x38,	0x39,	0x3a,	0x3b,	0x3c,	0x3d,	0x3e,	0x3f,
+	0x40,	0x41,	0x42,	0x43,	0x44,	0x45,	0x46,	0x47,
+	0x48,	0x49,	0x4a,	0x4b,	0x4c,	0x4d,	0x4e,	0x4f,
+	0x50,	0x51,	0x52,	0x53,	0x54,	0x55,	0x56,	0x57,
+	0x58,	0x59,	0x5a,	0x5b,	0x5c,	0x5d,	0x5e,	0x5f,
+	0x60,	'A',	'B',	'C',	'D',	'E',	'F',	'G',
+	'H',	'I',	'J',	'K',	'L',	'M',	'N',	'O',
+	'P',	'Q',	'R',	'S',	'T',	'U',	'V',	'W',
+	'X',	'Y',	'Z',	0x7b,	0x7c,	0x7d,	0x7e,	0x7f,
+	0x80,	0x81,	0x82,	0x83,	0x84,	0x85,	0x86,	0x87,
+	0x88,	0x89,	0x8a,	0x8b,	0x8c,	0x8d,	0x8e,	0x8f,
+	0x90,	0x91,	0x92,	0x93,	0x94,	0x95,	0x96,	0x97,
+	0x98,	0x99,	0x9a,	0x9b,	0x9c,	0x9d,	0x9e,	0x9f,
+	0xa0,	0xa1,	0xa2,	0xa3,	0xa4,	0xa5,	0xa6,	0xa7,
+	0xa8,	0xa9,	0xaa,	0xab,	0xac,	0xad,	0xae,	0xaf,
+	0xb0,	0xb1,	0xb2,	0xb3,	0xb4,	0xb5,	0xb6,	0xb7,
+	0xb8,	0xb9,	0xba,	0xbb,	0xbc,	0xbd,	0xbe,	0xbf,
+	0xc0,	0xc1,	0xc2,	0xc3,	0xc4,	0xc5,	0xc6,	0xc7,
+	0xc8,	0xc9,	0xca,	0xcb,	0xcc,	0xcd,	0xce,	0xcf,
+	0xd0,	0xd1,	0xd2,	0xd3,	0xd4,	0xd5,	0xd6,	0xd7,
+	0xd8,	0xd9,	0xda,	0xdb,	0xdc,	0xdd,	0xde,	0xdf,
+	0xe0,	0xe1,	0xe2,	0xe3,	0xe4,	0xe5,	0xe6,	0xe7,
+	0xe8,	0xe9,	0xea,	0xeb,	0xec,	0xed,	0xee,	0xef,
+	0xf0,	0xf1,	0xf2,	0xf3,	0xf4,	0xf5,	0xf6,	0xf7,
+	0xf8,	0xf9,	0xfa,	0xfb,	0xfc,	0xfd,	0xfe,	0xff
+};
+
+const short *_toupper_tab_ = _C_toupper_;
+
+#endif
diff --git a/libc/bionic/wctype.cpp b/libc/bionic/wctype.cpp
index 061f55a..082dada 100644
--- a/libc/bionic/wctype.cpp
+++ b/libc/bionic/wctype.cpp
@@ -129,7 +129,9 @@
 
 wint_t towupper(wint_t wc) {
   if (wc < 0x80) {
-    if (wc >= 'a' && wc <= 'z') return wc & 0xdf;
+    // Using EOR rather than AND makes no difference on arm, but saves an
+    // instruction on arm64.
+    if (wc >= 'a' && wc <= 'z') return wc ^ 0x20;
     return wc;
   }