diff --git a/llvm/lib/Support/VersionTuple.cpp b/llvm/lib/Support/VersionTuple.cpp
new file mode 100644
index 0000000..3f219bf
--- /dev/null
+++ b/llvm/lib/Support/VersionTuple.cpp
@@ -0,0 +1,110 @@
+//===- VersionTuple.cpp - Version Number Handling ---------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the VersionTuple class, which represents a version in
+// the form major[.minor[.subminor]].
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/Support/VersionTuple.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+std::string VersionTuple::getAsString() const {
+  std::string Result;
+  {
+    llvm::raw_string_ostream Out(Result);
+    Out << *this;
+  }
+  return Result;
+}
+
+raw_ostream &llvm::operator<<(raw_ostream &Out, const VersionTuple &V) {
+  Out << V.getMajor();
+  if (Optional<unsigned> Minor = V.getMinor())
+    Out << '.' << *Minor;
+  if (Optional<unsigned> Subminor = V.getSubminor())
+    Out << '.' << *Subminor;
+  if (Optional<unsigned> Build = V.getBuild())
+    Out << '.' << *Build;
+  return Out;
+}
+
+static bool parseInt(StringRef &input, unsigned &value) {
+  assert(value == 0);
+  if (input.empty())
+    return true;
+
+  char next = input[0];
+  input = input.substr(1);
+  if (next < '0' || next > '9')
+    return true;
+  value = (unsigned)(next - '0');
+
+  while (!input.empty()) {
+    next = input[0];
+    if (next < '0' || next > '9')
+      return false;
+    input = input.substr(1);
+    value = value * 10 + (unsigned)(next - '0');
+  }
+
+  return false;
+}
+
+bool VersionTuple::tryParse(StringRef input) {
+  unsigned major = 0, minor = 0, micro = 0, build = 0;
+
+  // Parse the major version, [0-9]+
+  if (parseInt(input, major))
+    return true;
+
+  if (input.empty()) {
+    *this = VersionTuple(major);
+    return false;
+  }
+
+  // If we're not done, parse the minor version, \.[0-9]+
+  if (input[0] != '.')
+    return true;
+  input = input.substr(1);
+  if (parseInt(input, minor))
+    return true;
+
+  if (input.empty()) {
+    *this = VersionTuple(major, minor);
+    return false;
+  }
+
+  // If we're not done, parse the micro version, \.[0-9]+
+  if (input[0] != '.')
+    return true;
+  input = input.substr(1);
+  if (parseInt(input, micro))
+    return true;
+
+  if (input.empty()) {
+    *this = VersionTuple(major, minor, micro);
+    return false;
+  }
+
+  // If we're not done, parse the micro version, \.[0-9]+
+  if (input[0] != '.')
+    return true;
+  input = input.substr(1);
+  if (parseInt(input, build))
+    return true;
+
+  // If we have characters left over, it's an error.
+  if (!input.empty())
+    return true;
+
+  *this = VersionTuple(major, minor, micro, build);
+  return false;
+}