diff --git a/include/llvm/ADT/StringRef.h b/include/llvm/ADT/StringRef.h
index 12e2c569def..269d16af618 100644
--- a/include/llvm/ADT/StringRef.h
+++ b/include/llvm/ADT/StringRef.h
@@ -97,6 +97,11 @@ namespace llvm {
               memcmp(Data, RHS.Data, RHS.Length) == 0);
     }
 
+    /// equals_lower - Check for string equality, ignoring case.
+    bool equals_lower(StringRef RHS) const {
+      return Length == RHS.Length && compare_lower(RHS) == 0;
+    }
+
     /// compare - Compare two strings; the result is -1, 0, or 1 if this string
     /// is lexicographically less than, equal to, or greater than the \arg RHS.
     int compare(StringRef RHS) const {
@@ -110,6 +115,9 @@ namespace llvm {
       return Length < RHS.Length ? -1 : 1;
     }
 
+    /// compare_lower - Compare two strings, ignoring case.
+    int compare_lower(StringRef RHS) const;
+
     /// str - Get the contents as an std::string.
     std::string str() const { return std::string(Data, Length); }
 
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 7e594a2ba25..2ca52a48c2a 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -22,7 +22,6 @@
 #include "llvm/DerivedTypes.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/SelectionDAG.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
@@ -2365,7 +2364,7 @@ getRegForInlineAsmConstraint(const std::string &Constraint,
   assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
 
   // Remove the braces from around the name.
-  std::string RegName(Constraint.begin()+1, Constraint.end()-1);
+  StringRef RegName(Constraint.data()+1, Constraint.size()-2);
 
   // Figure out which register class contains this reg.
   const TargetRegisterInfo *RI = TM.getRegisterInfo();
@@ -2388,7 +2387,7 @@ getRegForInlineAsmConstraint(const std::string &Constraint,
     
     for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end(); 
          I != E; ++I) {
-      if (StringsEqualNoCase(RegName, RI->getName(*I)))
+      if (RegName.equals_lower(RI->getName(*I)))
         return std::make_pair(*I, RC);
     }
   }
diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 6905edf19e1..51e11004f32 100644
--- a/lib/Support/StringRef.cpp
+++ b/lib/Support/StringRef.cpp
@@ -15,6 +15,26 @@ using namespace llvm;
 const size_t StringRef::npos;
 #endif
 
+static char ascii_tolower(char x) {
+  if (x >= 'A' && x <= 'Z')
+    return x - 'A' + 'a';
+  return x;
+}
+
+/// compare_lower - Compare strings, ignoring case.
+int StringRef::compare_lower(StringRef RHS) const {
+  for (size_t I = 0, E = std::min(Length, RHS.Length); I != E; ++I) {
+    char LHC = ascii_tolower(Data[I]);
+    char RHC = ascii_tolower(RHS.Data[I]);
+    if (LHC != RHC)
+      return LHC < RHC ? -1 : 1;
+  }
+
+  if (Length == RHS.Length)
+        return 0;
+  return Length < RHS.Length ? -1 : 1;
+}
+
 //===----------------------------------------------------------------------===//
 // String Searching
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1b671590401..7da1d1c631e 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -9595,14 +9595,14 @@ X86TargetLowering::getRegForInlineAsmConstraint(const std::string &Constraint,
     }
 
     // GCC allows "st(0)" to be called just plain "st".
-    if (StringsEqualNoCase("{st}", Constraint)) {
+    if (StringRef("{st}").equals_lower(Constraint)) {
       Res.first = X86::ST0;
       Res.second = X86::RFP80RegisterClass;
       return Res;
     }
 
     // flags -> EFLAGS
-    if (StringsEqualNoCase("{flags}", Constraint)) {
+    if (StringRef("{flags}").equals_lower(Constraint)) {
       Res.first = X86::EFLAGS;
       Res.second = X86::CCRRegisterClass;
       return Res;
diff --git a/tools/bugpoint/ToolRunner.cpp b/tools/bugpoint/ToolRunner.cpp
index 4551d419d73..3e63d8050c4 100644
--- a/tools/bugpoint/ToolRunner.cpp
+++ b/tools/bugpoint/ToolRunner.cpp
@@ -18,7 +18,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/Config/config.h"   // for HAVE_LINK_R
 #include <fstream>
 #include <sstream>
@@ -610,9 +609,10 @@ IsARMArchitecture(std::vector<std::string> Args)
 {
   for (std::vector<std::string>::const_iterator
          I = Args.begin(), E = Args.end(); I != E; ++I) {
-    if (!StringsEqualNoCase(*I, "-arch")) {
+    StringRef S(*I);
+    if (!S.equals_lower("-arch")) {
       ++I;
-      if ((I != E) && !StringsEqualNoCase(I->c_str(), "arm", strlen("arm"))) {
+      if (I != E && !S.substr(0, strlen("arm")).equals_lower("arm")) {
         return true;
       }
     }