Index: llvm/trunk/include/llvm/Support/DJB.h
===================================================================
--- llvm/trunk/include/llvm/Support/DJB.h
+++ llvm/trunk/include/llvm/Support/DJB.h
@@ -20,6 +20,10 @@
 
 /// The Bernstein hash function used by the DWARF accelerator tables.
 uint32_t djbHash(StringRef Buffer, uint32_t H = 5381);
+
+/// Computes the Bernstein hash after folding the input according to the Dwarf 5
+/// standard case folding rules.
+uint32_t caseFoldingDjbHash(StringRef Buffer, uint32_t H = 5381);
 } // namespace llvm
 
 #endif // LLVM_SUPPORT_DJB_H
Index: llvm/trunk/include/llvm/Support/Unicode.h
===================================================================
--- llvm/trunk/include/llvm/Support/Unicode.h
+++ llvm/trunk/include/llvm/Support/Unicode.h
@@ -60,6 +60,10 @@
 ///   * 1 for each of the remaining characters.
 int columnWidthUTF8(StringRef Text);
 
+/// Fold input unicode character according the the Simple unicode case folding
+/// rules.
+int foldCharSimple(int C);
+
 } // namespace unicode
 } // namespace sys
 } // namespace llvm
Index: llvm/trunk/lib/Support/CMakeLists.txt
===================================================================
--- llvm/trunk/lib/Support/CMakeLists.txt
+++ llvm/trunk/lib/Support/CMakeLists.txt
@@ -113,6 +113,7 @@
   Triple.cpp
   Twine.cpp
   Unicode.cpp
+  UnicodeCaseFold.cpp
   YAMLParser.cpp
   YAMLTraits.cpp
   raw_os_ostream.cpp
Index: llvm/trunk/lib/Support/DJB.cpp
===================================================================
--- llvm/trunk/lib/Support/DJB.cpp
+++ llvm/trunk/lib/Support/DJB.cpp
@@ -12,9 +12,85 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/DJB.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ConvertUTF.h"
+#include "llvm/Support/Unicode.h"
+
+using namespace llvm;
+
+static inline uint32_t djbHashChar(unsigned char C, uint32_t H) {
+  return (H << 5) + H + C;
+}
 
 uint32_t llvm::djbHash(StringRef Buffer, uint32_t H) {
-  for (char C : Buffer.bytes())
-    H = ((H << 5) + H) + C;
+  for (unsigned char C : Buffer.bytes())
+    H = djbHashChar(C, H);
+  return H;
+}
+
+static UTF32 chopOneUTF32(StringRef &Buffer) {
+  UTF32 C;
+  const UTF8 *const Begin8Const =
+      reinterpret_cast<const UTF8 *>(Buffer.begin());
+  const UTF8 *Begin8 = Begin8Const;
+  UTF32 *Begin32 = &C;
+
+  // In lenient mode we will always end up with a "reasonable" value in C for
+  // non-empty input.
+  assert(!Buffer.empty());
+  ConvertUTF8toUTF32(&Begin8, reinterpret_cast<const UTF8 *>(Buffer.end()),
+                     &Begin32, &C + 1, lenientConversion);
+  Buffer = Buffer.drop_front(Begin8 - Begin8Const);
+  return C;
+}
+
+static StringRef toUTF8(UTF32 C, MutableArrayRef<UTF8> Storage) {
+  const UTF32 *Begin32 = &C;
+  UTF8 *Begin8 = Storage.begin();
+
+  // The case-folded output should always be a valid unicode character, so use
+  // strict mode here.
+  ConversionResult CR = ConvertUTF32toUTF8(&Begin32, &C + 1, &Begin8,
+                                           Storage.end(), strictConversion);
+  assert(CR == conversionOK && "Case folding produced invalid char?");
+  (void)CR;
+  return StringRef(reinterpret_cast<char *>(Storage.begin()),
+                   Begin8 - Storage.begin());
+}
+
+static UTF32 foldCharDwarf(UTF32 C) {
+  // DWARF v5 addition to the unicode folding rules.
+  // Fold "Latin Small Letter Dotless I" and "Latin Capital Letter I With Dot
+  // Above" into "i".
+  if (C == 0x130 || C == 0x131)
+    return 'i';
+  return sys::unicode::foldCharSimple(C);
+}
+
+static uint32_t caseFoldingDjbHashCharSlow(StringRef &Buffer, uint32_t H) {
+  UTF32 C = chopOneUTF32(Buffer);
+
+  C = foldCharDwarf(C);
+
+  std::array<UTF8, UNI_MAX_UTF8_BYTES_PER_CODE_POINT> Storage;
+  StringRef Folded = toUTF8(C, Storage);
+  return djbHash(Folded, H);
+}
+
+uint32_t llvm::caseFoldingDjbHash(StringRef Buffer, uint32_t H) {
+  while (!Buffer.empty()) {
+    unsigned char C = Buffer.front();
+    if (LLVM_LIKELY(C <= 0x7f)) {
+      // US-ASCII, encoded as one character in utf-8.
+      // This is by far the most common case, so handle this specially.
+      if (C >= 'A' && C <= 'Z')
+        C = 'a' + (C - 'A'); // fold uppercase into lowercase
+      H = djbHashChar(C, H);
+      Buffer = Buffer.drop_front();
+      continue;
+    }
+    H = caseFoldingDjbHashCharSlow(Buffer, H);
+  }
   return H;
 }
Index: llvm/trunk/lib/Support/UnicodeCaseFold.cpp
===================================================================
--- llvm/trunk/lib/Support/UnicodeCaseFold.cpp
+++ llvm/trunk/lib/Support/UnicodeCaseFold.cpp
@@ -0,0 +1,742 @@
+//===---------- Support/UnicodeCaseFold.cpp -------------------------------===//
+//
+// This file was generated by utils/unicode-case-fold.py from the Unicode
+// case folding database at
+//    http://www.unicode.org/Public/9.0.0/ucd/CaseFolding.txt
+//
+// To regenerate this file, run:
+//   utils/unicode-case-fold.py \
+//     "http://www.unicode.org/Public/9.0.0/ucd/CaseFolding.txt" \
+//     > lib/Support/UnicodeCaseFold.cpp
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Unicode.h"
+
+int llvm::sys::unicode::foldCharSimple(int C) {
+  if (C < 0x0041)
+    return C;
+  // 26 characters
+  if (C <= 0x005a)
+    return C + 32;
+  // MICRO SIGN
+  if (C == 0x00b5)
+    return 0x03bc;
+  if (C < 0x00c0)
+    return C;
+  // 23 characters
+  if (C <= 0x00d6)
+    return C + 32;
+  if (C < 0x00d8)
+    return C;
+  // 7 characters
+  if (C <= 0x00de)
+    return C + 32;
+  if (C < 0x0100)
+    return C;
+  // 24 characters
+  if (C <= 0x012e)
+    return C | 1;
+  if (C < 0x0132)
+    return C;
+  // 3 characters
+  if (C <= 0x0136)
+    return C | 1;
+  if (C < 0x0139)
+    return C;
+  // 8 characters
+  if (C <= 0x0147 && C % 2 == 1)
+    return C + 1;
+  if (C < 0x014a)
+    return C;
+  // 23 characters
+  if (C <= 0x0176)
+    return C | 1;
+  // LATIN CAPITAL LETTER Y WITH DIAERESIS
+  if (C == 0x0178)
+    return 0x00ff;
+  if (C < 0x0179)
+    return C;
+  // 3 characters
+  if (C <= 0x017d && C % 2 == 1)
+    return C + 1;
+  // LATIN SMALL LETTER LONG S
+  if (C == 0x017f)
+    return 0x0073;
+  // LATIN CAPITAL LETTER B WITH HOOK
+  if (C == 0x0181)
+    return 0x0253;
+  if (C < 0x0182)
+    return C;
+  // 2 characters
+  if (C <= 0x0184)
+    return C | 1;
+  // LATIN CAPITAL LETTER OPEN O
+  if (C == 0x0186)
+    return 0x0254;
+  // LATIN CAPITAL LETTER C WITH HOOK
+  if (C == 0x0187)
+    return 0x0188;
+  if (C < 0x0189)
+    return C;
+  // 2 characters
+  if (C <= 0x018a)
+    return C + 205;
+  // LATIN CAPITAL LETTER D WITH TOPBAR
+  if (C == 0x018b)
+    return 0x018c;
+  // LATIN CAPITAL LETTER REVERSED E
+  if (C == 0x018e)
+    return 0x01dd;
+  // LATIN CAPITAL LETTER SCHWA
+  if (C == 0x018f)
+    return 0x0259;
+  // LATIN CAPITAL LETTER OPEN E
+  if (C == 0x0190)
+    return 0x025b;
+  // LATIN CAPITAL LETTER F WITH HOOK
+  if (C == 0x0191)
+    return 0x0192;
+  // LATIN CAPITAL LETTER G WITH HOOK
+  if (C == 0x0193)
+    return 0x0260;
+  // LATIN CAPITAL LETTER GAMMA
+  if (C == 0x0194)
+    return 0x0263;
+  // LATIN CAPITAL LETTER IOTA
+  if (C == 0x0196)
+    return 0x0269;
+  // LATIN CAPITAL LETTER I WITH STROKE
+  if (C == 0x0197)
+    return 0x0268;
+  // LATIN CAPITAL LETTER K WITH HOOK
+  if (C == 0x0198)
+    return 0x0199;
+  // LATIN CAPITAL LETTER TURNED M
+  if (C == 0x019c)
+    return 0x026f;
+  // LATIN CAPITAL LETTER N WITH LEFT HOOK
+  if (C == 0x019d)
+    return 0x0272;
+  // LATIN CAPITAL LETTER O WITH MIDDLE TILDE
+  if (C == 0x019f)
+    return 0x0275;
+  if (C < 0x01a0)
+    return C;
+  // 3 characters
+  if (C <= 0x01a4)
+    return C | 1;
+  // LATIN LETTER YR
+  if (C == 0x01a6)
+    return 0x0280;
+  // LATIN CAPITAL LETTER TONE TWO
+  if (C == 0x01a7)
+    return 0x01a8;
+  // LATIN CAPITAL LETTER ESH
+  if (C == 0x01a9)
+    return 0x0283;
+  // LATIN CAPITAL LETTER T WITH HOOK
+  if (C == 0x01ac)
+    return 0x01ad;
+  // LATIN CAPITAL LETTER T WITH RETROFLEX HOOK
+  if (C == 0x01ae)
+    return 0x0288;
+  // LATIN CAPITAL LETTER U WITH HORN
+  if (C == 0x01af)
+    return 0x01b0;
+  if (C < 0x01b1)
+    return C;
+  // 2 characters
+  if (C <= 0x01b2)
+    return C + 217;
+  if (C < 0x01b3)
+    return C;
+  // 2 characters
+  if (C <= 0x01b5 && C % 2 == 1)
+    return C + 1;
+  // LATIN CAPITAL LETTER EZH
+  if (C == 0x01b7)
+    return 0x0292;
+  if (C < 0x01b8)
+    return C;
+  // 2 characters
+  if (C <= 0x01bc && C % 4 == 0)
+    return C + 1;
+  // LATIN CAPITAL LETTER DZ WITH CARON
+  if (C == 0x01c4)
+    return 0x01c6;
+  // LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON
+  if (C == 0x01c5)
+    return 0x01c6;
+  // LATIN CAPITAL LETTER LJ
+  if (C == 0x01c7)
+    return 0x01c9;
+  // LATIN CAPITAL LETTER L WITH SMALL LETTER J
+  if (C == 0x01c8)
+    return 0x01c9;
+  // LATIN CAPITAL LETTER NJ
+  if (C == 0x01ca)
+    return 0x01cc;
+  if (C < 0x01cb)
+    return C;
+  // 9 characters
+  if (C <= 0x01db && C % 2 == 1)
+    return C + 1;
+  if (C < 0x01de)
+    return C;
+  // 9 characters
+  if (C <= 0x01ee)
+    return C | 1;
+  // LATIN CAPITAL LETTER DZ
+  if (C == 0x01f1)
+    return 0x01f3;
+  if (C < 0x01f2)
+    return C;
+  // 2 characters
+  if (C <= 0x01f4)
+    return C | 1;
+  // LATIN CAPITAL LETTER HWAIR
+  if (C == 0x01f6)
+    return 0x0195;
+  // LATIN CAPITAL LETTER WYNN
+  if (C == 0x01f7)
+    return 0x01bf;
+  if (C < 0x01f8)
+    return C;
+  // 20 characters
+  if (C <= 0x021e)
+    return C | 1;
+  // LATIN CAPITAL LETTER N WITH LONG RIGHT LEG
+  if (C == 0x0220)
+    return 0x019e;
+  if (C < 0x0222)
+    return C;
+  // 9 characters
+  if (C <= 0x0232)
+    return C | 1;
+  // LATIN CAPITAL LETTER A WITH STROKE
+  if (C == 0x023a)
+    return 0x2c65;
+  // LATIN CAPITAL LETTER C WITH STROKE
+  if (C == 0x023b)
+    return 0x023c;
+  // LATIN CAPITAL LETTER L WITH BAR
+  if (C == 0x023d)
+    return 0x019a;
+  // LATIN CAPITAL LETTER T WITH DIAGONAL STROKE
+  if (C == 0x023e)
+    return 0x2c66;
+  // LATIN CAPITAL LETTER GLOTTAL STOP
+  if (C == 0x0241)
+    return 0x0242;
+  // LATIN CAPITAL LETTER B WITH STROKE
+  if (C == 0x0243)
+    return 0x0180;
+  // LATIN CAPITAL LETTER U BAR
+  if (C == 0x0244)
+    return 0x0289;
+  // LATIN CAPITAL LETTER TURNED V
+  if (C == 0x0245)
+    return 0x028c;
+  if (C < 0x0246)
+    return C;
+  // 5 characters
+  if (C <= 0x024e)
+    return C | 1;
+  // COMBINING GREEK YPOGEGRAMMENI
+  if (C == 0x0345)
+    return 0x03b9;
+  if (C < 0x0370)
+    return C;
+  // 2 characters
+  if (C <= 0x0372)
+    return C | 1;
+  // GREEK CAPITAL LETTER PAMPHYLIAN DIGAMMA
+  if (C == 0x0376)
+    return 0x0377;
+  // GREEK CAPITAL LETTER YOT
+  if (C == 0x037f)
+    return 0x03f3;
+  // GREEK CAPITAL LETTER ALPHA WITH TONOS
+  if (C == 0x0386)
+    return 0x03ac;
+  if (C < 0x0388)
+    return C;
+  // 3 characters
+  if (C <= 0x038a)
+    return C + 37;
+  // GREEK CAPITAL LETTER OMICRON WITH TONOS
+  if (C == 0x038c)
+    return 0x03cc;
+  if (C < 0x038e)
+    return C;
+  // 2 characters
+  if (C <= 0x038f)
+    return C + 63;
+  if (C < 0x0391)
+    return C;
+  // 17 characters
+  if (C <= 0x03a1)
+    return C + 32;
+  if (C < 0x03a3)
+    return C;
+  // 9 characters
+  if (C <= 0x03ab)
+    return C + 32;
+  // GREEK SMALL LETTER FINAL SIGMA
+  if (C == 0x03c2)
+    return 0x03c3;
+  // GREEK CAPITAL KAI SYMBOL
+  if (C == 0x03cf)
+    return 0x03d7;
+  // GREEK BETA SYMBOL
+  if (C == 0x03d0)
+    return 0x03b2;
+  // GREEK THETA SYMBOL
+  if (C == 0x03d1)
+    return 0x03b8;
+  // GREEK PHI SYMBOL
+  if (C == 0x03d5)
+    return 0x03c6;
+  // GREEK PI SYMBOL
+  if (C == 0x03d6)
+    return 0x03c0;
+  if (C < 0x03d8)
+    return C;
+  // 12 characters
+  if (C <= 0x03ee)
+    return C | 1;
+  // GREEK KAPPA SYMBOL
+  if (C == 0x03f0)
+    return 0x03ba;
+  // GREEK RHO SYMBOL
+  if (C == 0x03f1)
+    return 0x03c1;
+  // GREEK CAPITAL THETA SYMBOL
+  if (C == 0x03f4)
+    return 0x03b8;
+  // GREEK LUNATE EPSILON SYMBOL
+  if (C == 0x03f5)
+    return 0x03b5;
+  // GREEK CAPITAL LETTER SHO
+  if (C == 0x03f7)
+    return 0x03f8;
+  // GREEK CAPITAL LUNATE SIGMA SYMBOL
+  if (C == 0x03f9)
+    return 0x03f2;
+  // GREEK CAPITAL LETTER SAN
+  if (C == 0x03fa)
+    return 0x03fb;
+  if (C < 0x03fd)
+    return C;
+  // 3 characters
+  if (C <= 0x03ff)
+    return C + -130;
+  if (C < 0x0400)
+    return C;
+  // 16 characters
+  if (C <= 0x040f)
+    return C + 80;
+  if (C < 0x0410)
+    return C;
+  // 32 characters
+  if (C <= 0x042f)
+    return C + 32;
+  if (C < 0x0460)
+    return C;
+  // 17 characters
+  if (C <= 0x0480)
+    return C | 1;
+  if (C < 0x048a)
+    return C;
+  // 27 characters
+  if (C <= 0x04be)
+    return C | 1;
+  // CYRILLIC LETTER PALOCHKA
+  if (C == 0x04c0)
+    return 0x04cf;
+  if (C < 0x04c1)
+    return C;
+  // 7 characters
+  if (C <= 0x04cd && C % 2 == 1)
+    return C + 1;
+  if (C < 0x04d0)
+    return C;
+  // 48 characters
+  if (C <= 0x052e)
+    return C | 1;
+  if (C < 0x0531)
+    return C;
+  // 38 characters
+  if (C <= 0x0556)
+    return C + 48;
+  if (C < 0x10a0)
+    return C;
+  // 38 characters
+  if (C <= 0x10c5)
+    return C + 7264;
+  if (C < 0x10c7)
+    return C;
+  // 2 characters
+  if (C <= 0x10cd && C % 6 == 5)
+    return C + 7264;
+  if (C < 0x13f8)
+    return C;
+  // 6 characters
+  if (C <= 0x13fd)
+    return C + -8;
+  // CYRILLIC SMALL LETTER ROUNDED VE
+  if (C == 0x1c80)
+    return 0x0432;
+  // CYRILLIC SMALL LETTER LONG-LEGGED DE
+  if (C == 0x1c81)
+    return 0x0434;
+  // CYRILLIC SMALL LETTER NARROW O
+  if (C == 0x1c82)
+    return 0x043e;
+  if (C < 0x1c83)
+    return C;
+  // 2 characters
+  if (C <= 0x1c84)
+    return C + -6210;
+  // CYRILLIC SMALL LETTER THREE-LEGGED TE
+  if (C == 0x1c85)
+    return 0x0442;
+  // CYRILLIC SMALL LETTER TALL HARD SIGN
+  if (C == 0x1c86)
+    return 0x044a;
+  // CYRILLIC SMALL LETTER TALL YAT
+  if (C == 0x1c87)
+    return 0x0463;
+  // CYRILLIC SMALL LETTER UNBLENDED UK
+  if (C == 0x1c88)
+    return 0xa64b;
+  if (C < 0x1e00)
+    return C;
+  // 75 characters
+  if (C <= 0x1e94)
+    return C | 1;
+  // LATIN SMALL LETTER LONG S WITH DOT ABOVE
+  if (C == 0x1e9b)
+    return 0x1e61;
+  // LATIN CAPITAL LETTER SHARP S
+  if (C == 0x1e9e)
+    return 0x00df;
+  if (C < 0x1ea0)
+    return C;
+  // 48 characters
+  if (C <= 0x1efe)
+    return C | 1;
+  if (C < 0x1f08)
+    return C;
+  // 8 characters
+  if (C <= 0x1f0f)
+    return C + -8;
+  if (C < 0x1f18)
+    return C;
+  // 6 characters
+  if (C <= 0x1f1d)
+    return C + -8;
+  if (C < 0x1f28)
+    return C;
+  // 8 characters
+  if (C <= 0x1f2f)
+    return C + -8;
+  if (C < 0x1f38)
+    return C;
+  // 8 characters
+  if (C <= 0x1f3f)
+    return C + -8;
+  if (C < 0x1f48)
+    return C;
+  // 6 characters
+  if (C <= 0x1f4d)
+    return C + -8;
+  if (C < 0x1f59)
+    return C;
+  // 4 characters
+  if (C <= 0x1f5f && C % 2 == 1)
+    return C + -8;
+  if (C < 0x1f68)
+    return C;
+  // 8 characters
+  if (C <= 0x1f6f)
+    return C + -8;
+  if (C < 0x1f88)
+    return C;
+  // 8 characters
+  if (C <= 0x1f8f)
+    return C + -8;
+  if (C < 0x1f98)
+    return C;
+  // 8 characters
+  if (C <= 0x1f9f)
+    return C + -8;
+  if (C < 0x1fa8)
+    return C;
+  // 8 characters
+  if (C <= 0x1faf)
+    return C + -8;
+  if (C < 0x1fb8)
+    return C;
+  // 2 characters
+  if (C <= 0x1fb9)
+    return C + -8;
+  if (C < 0x1fba)
+    return C;
+  // 2 characters
+  if (C <= 0x1fbb)
+    return C + -74;
+  // GREEK CAPITAL LETTER ALPHA WITH PROSGEGRAMMENI
+  if (C == 0x1fbc)
+    return 0x1fb3;
+  // GREEK PROSGEGRAMMENI
+  if (C == 0x1fbe)
+    return 0x03b9;
+  if (C < 0x1fc8)
+    return C;
+  // 4 characters
+  if (C <= 0x1fcb)
+    return C + -86;
+  // GREEK CAPITAL LETTER ETA WITH PROSGEGRAMMENI
+  if (C == 0x1fcc)
+    return 0x1fc3;
+  if (C < 0x1fd8)
+    return C;
+  // 2 characters
+  if (C <= 0x1fd9)
+    return C + -8;
+  if (C < 0x1fda)
+    return C;
+  // 2 characters
+  if (C <= 0x1fdb)
+    return C + -100;
+  if (C < 0x1fe8)
+    return C;
+  // 2 characters
+  if (C <= 0x1fe9)
+    return C + -8;
+  if (C < 0x1fea)
+    return C;
+  // 2 characters
+  if (C <= 0x1feb)
+    return C + -112;
+  // GREEK CAPITAL LETTER RHO WITH DASIA
+  if (C == 0x1fec)
+    return 0x1fe5;
+  if (C < 0x1ff8)
+    return C;
+  // 2 characters
+  if (C <= 0x1ff9)
+    return C + -128;
+  if (C < 0x1ffa)
+    return C;
+  // 2 characters
+  if (C <= 0x1ffb)
+    return C + -126;
+  // GREEK CAPITAL LETTER OMEGA WITH PROSGEGRAMMENI
+  if (C == 0x1ffc)
+    return 0x1ff3;
+  // OHM SIGN
+  if (C == 0x2126)
+    return 0x03c9;
+  // KELVIN SIGN
+  if (C == 0x212a)
+    return 0x006b;
+  // ANGSTROM SIGN
+  if (C == 0x212b)
+    return 0x00e5;
+  // TURNED CAPITAL F
+  if (C == 0x2132)
+    return 0x214e;
+  if (C < 0x2160)
+    return C;
+  // 16 characters
+  if (C <= 0x216f)
+    return C + 16;
+  // ROMAN NUMERAL REVERSED ONE HUNDRED
+  if (C == 0x2183)
+    return 0x2184;
+  if (C < 0x24b6)
+    return C;
+  // 26 characters
+  if (C <= 0x24cf)
+    return C + 26;
+  if (C < 0x2c00)
+    return C;
+  // 47 characters
+  if (C <= 0x2c2e)
+    return C + 48;
+  // LATIN CAPITAL LETTER L WITH DOUBLE BAR
+  if (C == 0x2c60)
+    return 0x2c61;
+  // LATIN CAPITAL LETTER L WITH MIDDLE TILDE
+  if (C == 0x2c62)
+    return 0x026b;
+  // LATIN CAPITAL LETTER P WITH STROKE
+  if (C == 0x2c63)
+    return 0x1d7d;
+  // LATIN CAPITAL LETTER R WITH TAIL
+  if (C == 0x2c64)
+    return 0x027d;
+  if (C < 0x2c67)
+    return C;
+  // 3 characters
+  if (C <= 0x2c6b && C % 2 == 1)
+    return C + 1;
+  // LATIN CAPITAL LETTER ALPHA
+  if (C == 0x2c6d)
+    return 0x0251;
+  // LATIN CAPITAL LETTER M WITH HOOK
+  if (C == 0x2c6e)
+    return 0x0271;
+  // LATIN CAPITAL LETTER TURNED A
+  if (C == 0x2c6f)
+    return 0x0250;
+  // LATIN CAPITAL LETTER TURNED ALPHA
+  if (C == 0x2c70)
+    return 0x0252;
+  if (C < 0x2c72)
+    return C;
+  // 2 characters
+  if (C <= 0x2c75 && C % 3 == 2)
+    return C + 1;
+  if (C < 0x2c7e)
+    return C;
+  // 2 characters
+  if (C <= 0x2c7f)
+    return C + -10815;
+  if (C < 0x2c80)
+    return C;
+  // 50 characters
+  if (C <= 0x2ce2)
+    return C | 1;
+  if (C < 0x2ceb)
+    return C;
+  // 2 characters
+  if (C <= 0x2ced && C % 2 == 1)
+    return C + 1;
+  if (C < 0x2cf2)
+    return C;
+  // 2 characters
+  if (C <= 0xa640 && C % 31054 == 11506)
+    return C + 1;
+  if (C < 0xa642)
+    return C;
+  // 22 characters
+  if (C <= 0xa66c)
+    return C | 1;
+  if (C < 0xa680)
+    return C;
+  // 14 characters
+  if (C <= 0xa69a)
+    return C | 1;
+  if (C < 0xa722)
+    return C;
+  // 7 characters
+  if (C <= 0xa72e)
+    return C | 1;
+  if (C < 0xa732)
+    return C;
+  // 31 characters
+  if (C <= 0xa76e)
+    return C | 1;
+  if (C < 0xa779)
+    return C;
+  // 2 characters
+  if (C <= 0xa77b && C % 2 == 1)
+    return C + 1;
+  // LATIN CAPITAL LETTER INSULAR G
+  if (C == 0xa77d)
+    return 0x1d79;
+  if (C < 0xa77e)
+    return C;
+  // 5 characters
+  if (C <= 0xa786)
+    return C | 1;
+  // LATIN CAPITAL LETTER SALTILLO
+  if (C == 0xa78b)
+    return 0xa78c;
+  // LATIN CAPITAL LETTER TURNED H
+  if (C == 0xa78d)
+    return 0x0265;
+  if (C < 0xa790)
+    return C;
+  // 2 characters
+  if (C <= 0xa792)
+    return C | 1;
+  if (C < 0xa796)
+    return C;
+  // 10 characters
+  if (C <= 0xa7a8)
+    return C | 1;
+  // LATIN CAPITAL LETTER H WITH HOOK
+  if (C == 0xa7aa)
+    return 0x0266;
+  // LATIN CAPITAL LETTER REVERSED OPEN E
+  if (C == 0xa7ab)
+    return 0x025c;
+  // LATIN CAPITAL LETTER SCRIPT G
+  if (C == 0xa7ac)
+    return 0x0261;
+  // LATIN CAPITAL LETTER L WITH BELT
+  if (C == 0xa7ad)
+    return 0x026c;
+  // LATIN CAPITAL LETTER SMALL CAPITAL I
+  if (C == 0xa7ae)
+    return 0x026a;
+  // LATIN CAPITAL LETTER TURNED K
+  if (C == 0xa7b0)
+    return 0x029e;
+  // LATIN CAPITAL LETTER TURNED T
+  if (C == 0xa7b1)
+    return 0x0287;
+  // LATIN CAPITAL LETTER J WITH CROSSED-TAIL
+  if (C == 0xa7b2)
+    return 0x029d;
+  // LATIN CAPITAL LETTER CHI
+  if (C == 0xa7b3)
+    return 0xab53;
+  if (C < 0xa7b4)
+    return C;
+  // 2 characters
+  if (C <= 0xa7b6)
+    return C | 1;
+  if (C < 0xab70)
+    return C;
+  // 80 characters
+  if (C <= 0xabbf)
+    return C + -38864;
+  if (C < 0xff21)
+    return C;
+  // 26 characters
+  if (C <= 0xff3a)
+    return C + 32;
+  if (C < 0x10400)
+    return C;
+  // 40 characters
+  if (C <= 0x10427)
+    return C + 40;
+  if (C < 0x104b0)
+    return C;
+  // 36 characters
+  if (C <= 0x104d3)
+    return C + 40;
+  if (C < 0x10c80)
+    return C;
+  // 51 characters
+  if (C <= 0x10cb2)
+    return C + 64;
+  if (C < 0x118a0)
+    return C;
+  // 32 characters
+  if (C <= 0x118bf)
+    return C + 32;
+  if (C < 0x1e900)
+    return C;
+  // 34 characters
+  if (C <= 0x1e921)
+    return C + 34;
+
+  return C;
+}
Index: llvm/trunk/unittests/Support/CMakeLists.txt
===================================================================
--- llvm/trunk/unittests/Support/CMakeLists.txt
+++ llvm/trunk/unittests/Support/CMakeLists.txt
@@ -19,6 +19,7 @@
   ConvertUTFTest.cpp
   DataExtractorTest.cpp
   DebugTest.cpp
+  DJBTest.cpp
   EndianStreamTest.cpp
   EndianTest.cpp
   ErrnoTest.cpp
Index: llvm/trunk/unittests/Support/DJBTest.cpp
===================================================================
--- llvm/trunk/unittests/Support/DJBTest.cpp
+++ llvm/trunk/unittests/Support/DJBTest.cpp
@@ -0,0 +1,96 @@
+//===---------- llvm/unittest/Support/DJBTest.cpp -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DJB.h"
+#include "llvm/ADT/Twine.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+TEST(DJBTest, caseFolding) {
+  struct TestCase {
+    StringLiteral One;
+    StringLiteral Two;
+  };
+
+  static constexpr TestCase Tests[] = {
+      {{"ASDF"}, {"asdf"}},
+      {{"qWeR"}, {"QwEr"}},
+      {{"qqqqqqqqqqqqqqqqqqqq"}, {"QQQQQQQQQQQQQQQQQQQQ"}},
+
+      {{"I"}, {"i"}},
+      // Latin Small Letter Dotless I
+      {{u8"\u0130"}, {"i"}},
+      // Latin Capital Letter I With Dot Above
+      {{u8"\u0131"}, {"i"}},
+
+      // Latin Capital Letter A With Grave
+      {{u8"\u00c0"}, {u8"\u00e0"}},
+      // Latin Capital Letter A With Macron
+      {{u8"\u0100"}, {u8"\u0101"}},
+      // Latin Capital Letter L With Acute
+      {{u8"\u0139"}, {u8"\u013a"}},
+      // Cyrillic Capital Letter Ie
+      {{u8"\u0415"}, {u8"\u0435"}},
+      // Latin Capital Letter A With Circumflex And Grave
+      {{u8"\u1ea6"}, {u8"\u1ea7"}},
+      // Kelvin Sign
+      {{u8"\u212a"}, {u8"\u006b"}},
+      // Glagolitic Capital Letter Chrivi
+      {{u8"\u2c1d"}, {u8"\u2c4d"}},
+      // Fullwidth Latin Capital Letter M
+      {{u8"\uff2d"}, {u8"\uff4d"}},
+      // Old Hungarian Capital Letter Ej
+      {{u8"\U00010c92"}, {u8"\U00010cd2"}},
+  };
+
+  for (const TestCase &T : Tests) {
+    SCOPED_TRACE("Comparing '" + T.One + "' and '" + T.Two + "'");
+    EXPECT_EQ(caseFoldingDjbHash(T.One), caseFoldingDjbHash(T.Two));
+  }
+}
+
+TEST(DJBTest, knownValuesLowerCase) {
+  struct TestCase {
+    StringLiteral Text;
+    uint32_t Hash;
+  };
+  static constexpr TestCase Tests[] = {
+      {{""}, 5381u},
+      {{"f"}, 177675u},
+      {{"fo"}, 5863386u},
+      {{"foo"}, 193491849u},
+      {{"foob"}, 2090263819u},
+      {{"fooba"}, 259229388u},
+      {{"foobar"}, 4259602622u},
+      {{"pneumonoultramicroscopicsilicovolcanoconiosis"}, 3999417781u},
+  };
+
+  for (const TestCase &T : Tests) {
+    SCOPED_TRACE("Text: '" + T.Text + "'");
+    EXPECT_EQ(T.Hash, djbHash(T.Text));
+    EXPECT_EQ(T.Hash, caseFoldingDjbHash(T.Text));
+    EXPECT_EQ(T.Hash, caseFoldingDjbHash(T.Text.upper()));
+  }
+}
+
+TEST(DJBTest, knownValuesUnicode) {
+  EXPECT_EQ(5866553u, djbHash(u8"\u0130"));
+  EXPECT_EQ(177678u, caseFoldingDjbHash(u8"\u0130"));
+  EXPECT_EQ(
+      1302161417u,
+      djbHash(
+          u8"\u0130\u0131\u00c0\u00e0\u0100\u0101\u0139\u013a\u0415\u0435\u1ea6"
+          u8"\u1ea7\u212a\u006b\u2c1d\u2c4d\uff2d\uff4d\U00010c92\U00010cd2"));
+  EXPECT_EQ(
+      1145571043u,
+      caseFoldingDjbHash(
+          u8"\u0130\u0131\u00c0\u00e0\u0100\u0101\u0139\u013a\u0415\u0435\u1ea6"
+          u8"\u1ea7\u212a\u006b\u2c1d\u2c4d\uff2d\uff4d\U00010c92\U00010cd2"));
+}
Index: llvm/trunk/utils/unicode-case-fold.py
===================================================================
--- llvm/trunk/utils/unicode-case-fold.py
+++ llvm/trunk/utils/unicode-case-fold.py
@@ -0,0 +1,137 @@
+#!/usr/bin/env python
+"""
+Unicode case folding database conversion utility
+
+Parses the database and generates a C++ function which implements the case
+folding algorithm. The database entries are of the form:
+
+  <code>; <status>; <mapping>; # <name>
+
+<status> can be one of four characters:
+  C - Common mappings
+  S - mappings for Simple case folding
+  F - mappings for Full case folding
+  T - special case for Turkish I characters
+
+Right now this generates a function which implements simple case folding (C+S
+entries).
+"""
+
+import sys
+import re
+import urllib2
+
+# This variable will body of the mappings function
+body = ""
+
+# Reads file line-by-line, extracts Common and Simple case fold mappings and
+# returns a (from_char, to_char, from_name) tuple.
+def mappings(f):
+    previous_from = -1
+    expr = re.compile(r'^(.*); [CS]; (.*); # (.*)')
+    for line in f:
+        m = expr.match(line)
+        if not m: continue
+        from_char = int(m.group(1), 16)
+        to_char = int(m.group(2), 16)
+        from_name = m.group(3)
+
+        if from_char <= previous_from:
+            raise Exception("Duplicate or unsorted characters in input")
+        yield from_char, to_char, from_name
+        previous_from = from_char
+
+# Computes the shift (to_char - from_char) in a mapping.
+def shift(mapping):
+    return mapping[1] - mapping[0]
+
+# Computes the stride (from_char2 - from_char1) of two mappings.
+def stride2(mapping1, mapping2):
+    return mapping2[0] - mapping1[0]
+
+# Computes the stride of a list of mappings. The list should have at least two
+# mappings. All mappings in the list are assumed to have the same stride.
+def stride(block):
+    return stride2(block[0], block[1])
+
+
+# b is a list of mappings. All the mappings are assumed to have the same
+# shift and the stride between adjecant mappings (if any) is constant.
+def dump_block(b):
+    global body
+
+    if len(b) == 1:
+        # Special case for handling blocks of length 1. We don't even need to
+        # emit the "if (C < X) return C" check below as all characters in this
+        # range will be caught by the "C < X" check emitted by the first
+        # non-trivial block.
+        body  += "  // {2}\n  if (C == {0:#06x})\n    return {1:#06x};\n".format(*b[0])
+        return
+
+    first = b[0][0]
+    last = first + stride(b) * (len(b)-1)
+    modulo = first % stride(b)
+
+    # All characters before this block map to themselves.
+    body += "  if (C < {0:#06x})\n    return C;\n".format(first)
+    body += "  // {0} characters\n".format(len(b))
+
+    # Generic pattern: check upper bound (lower bound is checked by the "if"
+    # above) and modulo of C, return C+shift.
+    pattern = "  if (C <= {0:#06x} && C % {1} == {2})\n    return C + {3};\n"
+
+    if stride(b) == 2 and shift(b[0]) == 1 and modulo == 0:
+        # Special case:
+        # We can elide the modulo-check because the expression "C|1" will map
+        # the intervening characters to themselves.
+        pattern = "  if (C <= {0:#06x})\n    return C | 1;\n"
+    elif stride(b) == 1:
+        # Another special case: X % 1 is always zero, so don't emit the
+        # modulo-check.
+        pattern = "  if (C <= {0:#06x})\n    return C + {3};\n"
+
+    body += pattern.format(last, stride(b), modulo, shift(b[0]))
+
+current_block = []
+f = urllib2.urlopen(sys.argv[1])
+for m in mappings(f):
+    if len(current_block) == 0:
+        current_block.append(m)
+        continue
+
+    if shift(current_block[0]) != shift(m):
+        # Incompatible shift, start a new block.
+        dump_block(current_block)
+        current_block = [m]
+        continue
+
+    if len(current_block) == 1 or stride(current_block) == stride2(current_block[-1], m):
+        current_block.append(m)
+        continue
+
+    # Incompatible stride, start a new block.
+    dump_block(current_block)
+    current_block = [m]
+f.close()
+
+dump_block(current_block)
+
+print '//===---------- Support/UnicodeCaseFold.cpp -------------------------------===//'
+print '//'
+print '// This file was generated by utils/unicode-case-fold.py from the Unicode'
+print '// case folding database at'
+print '//   ', sys.argv[1]
+print '//'
+print '// To regenerate this file, run:'
+print '//   utils/unicode-case-fold.py \\'
+print '//     "{}" \\'.format(sys.argv[1])
+print '//     > lib/Support/UnicodeCaseFold.cpp'
+print '//'
+print '//===----------------------------------------------------------------------===//'
+print ''
+print '#include "llvm/Support/Unicode.h"'
+print ''
+print "int llvm::sys::unicode::foldCharSimple(int C) {"
+print body
+print "  return C;"
+print "}"