diff --git a/llvm/lib/TableGen/Main.cpp b/llvm/lib/TableGen/Main.cpp
new file mode 100644
index 0000000..01bc55e
--- /dev/null
+++ b/llvm/lib/TableGen/Main.cpp
@@ -0,0 +1,124 @@
+//===- Main.cpp - Top-Level TableGen implementation -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// TableGen is a tool which can be used to build up a description of something,
+// then invoke one or more "tablegen backends" to emit information about the
+// description in some predefined format.  In practice, this is used by the LLVM
+// code generators to automate generation of a code generator through a
+// high-level description of the target.
+//
+//===----------------------------------------------------------------------===//
+
+#include "TGParser.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/system_error.h"
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/Record.h"
+#include "llvm/TableGen/TableGenAction.h"
+#include <algorithm>
+#include <cstdio>
+using namespace llvm;
+
+namespace {
+  cl::opt<std::string>
+  OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
+                 cl::init("-"));
+
+  cl::opt<std::string>
+  DependFilename("d", cl::desc("Dependency filename"), cl::value_desc("filename"),
+                 cl::init(""));
+
+  cl::opt<std::string>
+  InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
+
+  cl::list<std::string>
+  IncludeDirs("I", cl::desc("Directory of include files"),
+              cl::value_desc("directory"), cl::Prefix);
+}
+
+namespace llvm {
+
+int TableGenMain(char *argv0, TableGenAction &Action) {
+  RecordKeeper Records;
+
+  try {
+    // Parse the input file.
+    OwningPtr<MemoryBuffer> File;
+    if (error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename.c_str(), File)) {
+      errs() << "Could not open input file '" << InputFilename << "': "
+             << ec.message() <<"\n";
+      return 1;
+    }
+    MemoryBuffer *F = File.take();
+
+    // Tell SrcMgr about this buffer, which is what TGParser will pick up.
+    SrcMgr.AddNewSourceBuffer(F, SMLoc());
+
+    // Record the location of the include directory so that the lexer can find
+    // it later.
+    SrcMgr.setIncludeDirs(IncludeDirs);
+
+    TGParser Parser(SrcMgr, Records);
+
+    if (Parser.ParseFile())
+      return 1;
+
+    std::string Error;
+    tool_output_file Out(OutputFilename.c_str(), Error);
+    if (!Error.empty()) {
+      errs() << argv0 << ": error opening " << OutputFilename
+        << ":" << Error << "\n";
+      return 1;
+    }
+    if (!DependFilename.empty()) {
+      if (OutputFilename == "-") {
+        errs() << argv0 << ": the option -d must be used together with -o\n";
+        return 1;
+      }
+      tool_output_file DepOut(DependFilename.c_str(), Error);
+      if (!Error.empty()) {
+        errs() << argv0 << ": error opening " << DependFilename
+          << ":" << Error << "\n";
+        return 1;
+      }
+      DepOut.os() << OutputFilename << ":";
+      const std::vector<std::string> &Dependencies = Parser.getDependencies();
+      for (std::vector<std::string>::const_iterator I = Dependencies.begin(),
+                                                          E = Dependencies.end();
+           I != E; ++I) {
+        DepOut.os() << " " << (*I);
+      }
+      DepOut.os() << "\n";
+      DepOut.keep();
+    }
+
+    if (Action(Out.os(), Records))
+      return 1;
+
+    // Declare success.
+    Out.keep();
+    return 0;
+
+  } catch (const TGError &Error) {
+    PrintError(Error);
+  } catch (const std::string &Error) {
+    PrintError(Error);
+  } catch (const char *Error) {
+    PrintError(Error);
+  } catch (...) {
+    errs() << argv0 << ": Unknown unexpected exception occurred.\n";
+  }
+
+  return 1;
+}
+
+}