Index: include/llvm/Support/ParseHelper.h
===================================================================
--- /dev/null
+++ include/llvm/Support/ParseHelper.h
@@ -0,0 +1,64 @@
+//===- ParseHelper.h - Simple parser helper class ---------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the ParseHelper class, intended to help implement simple
+// parsers.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_PARSEHELPER_H
+#define LLVM_SUPPORT_PARSEHELPER_H
+
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+
+class ParseHelper
+{
+public:
+  ParseHelper(StringRef S)
+    : Begin(S.begin()), End(S.end()), C(Begin), P(Begin), PEnd(nullptr) {}
+
+  // Return true if string literal is next.
+  bool Next(StringRef S);
+
+  // Return true if number is next.
+  // Output N only if number is next.
+  bool Next(unsigned &N);
+
+  // Return true if string literal is found.
+  // When true, P marks begin-position of S in content.
+  bool Search(StringRef S, bool EnsureStartOfWord = false);
+
+  // Return true if a CloseBrace that closes the OpenBrace at the current nest
+  // level is found. When true, P marks begin-position of CloseBrace.
+  bool SearchClosingBrace(StringRef OpenBrace, StringRef CloseBrace);
+
+  // Advance 1-past previous next/search.
+  // Behavior is undefined if previous next/search failed.
+  bool Advance();
+
+  // Skip zero or more whitespace.
+  void SkipWhitespace();
+
+  // Return true if EOF reached.
+  bool Done();
+
+  const char * const Begin; // beginning of expected content
+  const char * const End;   // end of expected content (1-past)
+  const char *C;            // position of next char in content
+  const char *P;
+
+private:
+  const char *PEnd; // previous next/search subject end (1-past)
+};
+
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_PARSEHELPER_H
Index: lib/Support/CMakeLists.txt
===================================================================
--- lib/Support/CMakeLists.txt
+++ lib/Support/CMakeLists.txt
@@ -72,6 +72,7 @@
   MD5.cpp
   NativeFormatting.cpp
   Options.cpp
+  ParseHelper.cpp
   PluginLoader.cpp
   PrettyStackTrace.cpp
   RandomNumberGenerator.cpp
Index: lib/Support/ParseHelper.cpp
===================================================================
--- /dev/null
+++ lib/Support/ParseHelper.cpp
@@ -0,0 +1,114 @@
+//===- ParseHelper.cpp - Simple parser helper class -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the ParseHelper class, intended to help implement simple
+// parsers.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/ParseHelper.h"
+
+using namespace llvm;
+
+static bool isWhitespace(const char C) {
+  switch (C) {
+  case ' ': case '\t': case '\f':
+  case '\v': case '\n': case '\r':
+    return true;
+  default:
+    return false;
+  }
+}
+
+// Return true if string literal is next.
+bool ParseHelper::Next(StringRef S) {
+  P = C;
+  PEnd = C + S.size();
+  if (PEnd > End)
+    return false;
+  return !memcmp(P, S.data(), S.size());
+}
+
+// Return true if number is next.
+// Output N only if number is next.
+bool ParseHelper::Next(unsigned &N) {
+  unsigned TMP = 0;
+  P = C;
+  for (; P < End && P[0] >= '0' && P[0] <= '9'; ++P) {
+    TMP *= 10;
+    TMP += P[0] - '0';
+  }
+  if (P == C)
+    return false;
+  PEnd = P;
+  N = TMP;
+  return true;
+}
+
+// Return true if string literal is found.
+// When true, P marks begin-position of S in content.
+bool ParseHelper::Search(StringRef S, bool EnsureStartOfWord) {
+  do {
+    P = std::search(C, End, S.begin(), S.end());
+    PEnd = P + S.size();
+    if (P == End)
+      break;
+    if (!EnsureStartOfWord
+          // Check if string literal starts a new word.
+          || P == Begin || isWhitespace(P[-1])
+          // Or it could be preceded by the start of a comment.
+          || (P > (Begin + 1) && (P[-1] == '/' || P[-1] == '*')
+                              &&  P[-2] == '/'))
+      return true;
+    // Otherwise, skip and search again.
+  } while (Advance());
+  return false;
+}
+
+// Return true if a CloseBrace that closes the OpenBrace at the current nest
+// level is found. When true, P marks begin-position of CloseBrace.
+bool ParseHelper::SearchClosingBrace(StringRef OpenBrace, StringRef CloseBrace) {
+  unsigned Depth = 1;
+  P = C;
+  while (P < End) {
+    StringRef S(P, End - P);
+    if (S.startswith(OpenBrace)) {
+      ++Depth;
+      P += OpenBrace.size();
+    } else if (S.startswith(CloseBrace)) {
+      --Depth;
+      if (Depth == 0) {
+        PEnd = P + CloseBrace.size();
+        return true;
+      }
+      P += CloseBrace.size();
+    } else {
+      ++P;
+    }
+  }
+  return false;
+}
+
+// Advance 1-past previous next/search.
+// Behavior is undefined if previous next/search failed.
+bool ParseHelper::Advance() {
+  C = PEnd;
+  return C < End;
+}
+
+// Skip zero or more whitespace.
+void ParseHelper::SkipWhitespace() {
+  for (; C < End && isWhitespace(*C); ++C)
+    ;
+}
+
+// Return true if EOF reached.
+bool ParseHelper::Done() {
+  return !(C < End);
+}