diff --git a/include/llvm/Bitstream/BitCodes.h b/include/llvm/Bitstream/BitCodes.h
index 41a3de3b20e..9cd4e535a47 100644
--- a/include/llvm/Bitstream/BitCodes.h
+++ b/include/llvm/Bitstream/BitCodes.h
@@ -18,6 +18,7 @@
 #define LLVM_BITSTREAM_BITCODES_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
@@ -137,13 +138,7 @@ public:
   }
 
   /// isChar6 - Return true if this character is legal in the Char6 encoding.
-  static bool isChar6(char C) {
-    if (C >= 'a' && C <= 'z') return true;
-    if (C >= 'A' && C <= 'Z') return true;
-    if (C >= '0' && C <= '9') return true;
-    if (C == '.' || C == '_') return true;
-    return false;
-  }
+  static bool isChar6(char C) { return isAlnum(C) || C == '.' || C == '_'; }
   static unsigned EncodeChar6(char C) {
     if (C >= 'a' && C <= 'z') return C-'a';
     if (C >= 'A' && C <= 'Z') return C-'A'+26;
diff --git a/lib/IR/Mangler.cpp b/lib/IR/Mangler.cpp
index 8536503cb6d..674ba3cdaa2 100644
--- a/lib/IR/Mangler.cpp
+++ b/lib/IR/Mangler.cpp
@@ -12,6 +12,7 @@
 
 #include "llvm/IR/Mangler.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/IR/DataLayout.h"
@@ -186,8 +187,7 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
 
 // Check if the name needs quotes to be safe for the linker to interpret.
 static bool canBeUnquotedInDirective(char C) {
-  return (C >= 'a' && C <= 'z') || (C >= 'A' && C <= 'Z') ||
-         (C >= '0' && C <= '9') || C == '_' || C == '$' || C == '.' || C == '@';
+  return isAlnum(C) || C == '_' || C == '$' || C == '.' || C == '@';
 }
 
 static bool canBeUnquotedInDirective(StringRef Name) {
diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index 0d2d26b0eb4..620d3e7cffc 100644
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -109,8 +109,7 @@ MCAsmInfo::getExprForFDESymbol(const MCSymbol *Sym,
 }
 
 bool MCAsmInfo::isAcceptableChar(char C) const {
-  return (C >= 'a' && C <= 'z') || (C >= 'A' && C <= 'Z') ||
-         (C >= '0' && C <= '9') || C == '_' || C == '$' || C == '.' || C == '@';
+  return isAlnum(C) || C == '_' || C == '$' || C == '.' || C == '@';
 }
 
 bool MCAsmInfo::isValidUnquotedName(StringRef Name) const {
diff --git a/lib/Support/YAMLParser.cpp b/lib/Support/YAMLParser.cpp
index 17321177105..f68ba0d065c 100644
--- a/lib/Support/YAMLParser.cpp
+++ b/lib/Support/YAMLParser.cpp
@@ -981,17 +981,9 @@ void Scanner::advanceWhile(SkipWhileFunc Func) {
   Current = Final;
 }
 
-static bool is_ns_hex_digit(const char C) {
-  return    (C >= '0' && C <= '9')
-         || (C >= 'a' && C <= 'z')
-         || (C >= 'A' && C <= 'Z');
-}
+static bool is_ns_hex_digit(const char C) { return isAlnum(C); }
 
-static bool is_ns_word_char(const char C) {
-  return    C == '-'
-         || (C >= 'a' && C <= 'z')
-         || (C >= 'A' && C <= 'Z');
-}
+static bool is_ns_word_char(const char C) { return C == '-' || isAlpha(C); }
 
 void Scanner::scan_ns_uri_char() {
   while (true) {
diff --git a/utils/TableGen/AsmMatcherEmitter.cpp b/utils/TableGen/AsmMatcherEmitter.cpp
index 48b7014e84a..9d304910ba4 100644
--- a/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/utils/TableGen/AsmMatcherEmitter.cpp
@@ -1112,9 +1112,7 @@ static std::string getEnumNameForToken(StringRef Str) {
     case '-': Res += "_MINUS_"; break;
     case '#': Res += "_HASH_"; break;
     default:
-      if ((*it >= 'A' && *it <= 'Z') ||
-          (*it >= 'a' && *it <= 'z') ||
-          (*it >= '0' && *it <= '9'))
+      if (isAlnum(*it))
         Res += *it;
       else
         Res += "_" + utostr((unsigned) *it) + "_";
diff --git a/utils/TableGen/AsmWriterEmitter.cpp b/utils/TableGen/AsmWriterEmitter.cpp
index a09ea775808..92df204475b 100644
--- a/utils/TableGen/AsmWriterEmitter.cpp
+++ b/utils/TableGen/AsmWriterEmitter.cpp
@@ -713,9 +713,7 @@ public:
         ++Next;
     } else {
       // $name, just eat the usual suspects.
-      while (I != End &&
-             ((*I >= 'a' && *I <= 'z') || (*I >= 'A' && *I <= 'Z') ||
-              (*I >= '0' && *I <= '9') || *I == '_'))
+      while (I != End && (isAlnum(*I) || *I == '_'))
         ++I;
       Next = I;
     }
diff --git a/utils/TableGen/AsmWriterInst.cpp b/utils/TableGen/AsmWriterInst.cpp
index 24d29ffc28e..cf24f79334c 100644
--- a/utils/TableGen/AsmWriterInst.cpp
+++ b/utils/TableGen/AsmWriterInst.cpp
@@ -18,12 +18,7 @@
 
 using namespace llvm;
 
-static bool isIdentChar(char C) {
-  return (C >= 'a' && C <= 'z') ||
-  (C >= 'A' && C <= 'Z') ||
-  (C >= '0' && C <= '9') ||
-  C == '_';
-}
+static bool isIdentChar(char C) { return isAlnum(C) || C == '_'; }
 
 std::string AsmWriterOperand::getCode(bool PassSubtarget) const {
   if (OperandType == isLiteralTextOperand) {