diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index 238f905..ea2f827 100644
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -39,8 +39,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
-#include <fstream>
-
 using namespace llvm;
 
 namespace {
@@ -65,7 +63,7 @@
     const bool allowPhysDoubleDefs;
 
     const char *const OutFileName;
-    std::ostream *OS;
+    raw_ostream *OS;
     const MachineFunction *MF;
     const TargetMachine *TM;
     const TargetRegisterInfo *TRI;
@@ -173,21 +171,24 @@
 MachineVer("machineverifier", "Verify generated machine code");
 static const PassInfo *const MachineVerifyID = &MachineVer;
 
-FunctionPass *
-llvm::createMachineVerifierPass(bool allowPhysDoubleDefs)
-{
+FunctionPass *llvm::createMachineVerifierPass(bool allowPhysDoubleDefs) {
   return new MachineVerifier(allowPhysDoubleDefs);
 }
 
-bool
-MachineVerifier::runOnMachineFunction(MachineFunction &MF)
-{
-  std::ofstream OutFile;
+bool MachineVerifier::runOnMachineFunction(MachineFunction &MF) {
+  raw_ostream *OutFile = 0;
   if (OutFileName) {
-    OutFile.open(OutFileName, std::ios::out | std::ios::app);
-    OS = &OutFile;
+    std::string ErrorInfo;
+    OutFile = new raw_fd_ostream(OutFileName, ErrorInfo,
+                                 raw_fd_ostream::F_Append);
+    if (!ErrorInfo.empty()) {
+      errs() << "Error opening '" << OutFileName << "': " << ErrorInfo << '\n';
+      exit(1);
+    }
+    
+    OS = OutFile;
   } else {
-    OS = cerr.stream();
+    OS = &errs();
   }
 
   foundErrors = 0;
@@ -212,14 +213,10 @@
   }
   visitMachineFunctionAfter();
 
-  if (OutFileName)
-    OutFile.close();
-  else if (foundErrors) {
-    std::string msg;
-    raw_string_ostream Msg(msg);
-    Msg << "Found " << foundErrors << " machine code errors.";
-    llvm_report_error(Msg.str());
-  }
+  if (OutFile)
+    delete OutFile;
+  else if (foundErrors)
+    llvm_report_error("Found "+Twine(foundErrors)+" machine code errors.");
 
   // Clean up.
   regsLive.clear();
@@ -234,7 +231,7 @@
 
 void MachineVerifier::report(const char *msg, const MachineFunction *MF) {
   assert(MF);
-  *OS << "\n";
+  *OS << '\n';
   if (!foundErrors++)
     MF->print(*OS);
   *OS << "*** Bad machine code: " << msg << " ***\n"
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index 94507bd..2e15111 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -322,8 +322,12 @@
 /// occurs, information about the error is put into ErrorInfo, and the
 /// stream should be immediately destroyed; the string will be empty
 /// if no error occurred.
-raw_fd_ostream::raw_fd_ostream(const char *Filename, bool Binary, bool Force,
-                               std::string &ErrorInfo) : pos(0) {
+raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
+                               unsigned Flags) : pos(0) {
+  // Verify that we don't have both "append" and "force".
+  assert((!(Flags & F_Force) || !(Flags & F_Append)) &&
+         "Cannot specify both 'force' and 'append' file creation flags!");
+  
   ErrorInfo.clear();
 
   // Handle "-" as stdout.
@@ -331,20 +335,26 @@
     FD = STDOUT_FILENO;
     // If user requested binary then put stdout into binary mode if
     // possible.
-    if (Binary)
+    if (Flags & F_Binary)
       sys::Program::ChangeStdoutToBinary();
     ShouldClose = false;
     return;
   }
   
-  int Flags = O_WRONLY|O_CREAT|O_TRUNC;
+  int OpenFlags = O_WRONLY|O_CREAT;
 #ifdef O_BINARY
   if (Binary)
-    Flags |= O_BINARY;
+    OpenFlags |= O_BINARY;
 #endif
-  if (!Force)
-    Flags |= O_EXCL;
-  FD = open(Filename, Flags, 0664);
+  
+  if (Flags & F_Force)
+    OpenFlags |= O_TRUNC;
+  else if (Flags & F_Append)
+    OpenFlags |= O_APPEND;
+  else
+    OpenFlags |= O_EXCL;
+  
+  FD = open(Filename, OpenFlags, 0664);
   if (FD < 0) {
     ErrorInfo = "Error opening output file '" + std::string(Filename) + "'";
     ShouldClose = false;
@@ -354,14 +364,14 @@
 }
 
 raw_fd_ostream::~raw_fd_ostream() {
-  if (FD >= 0) {
-    flush();
-    if (ShouldClose)
-      if (::close(FD) != 0)
-        error_detected();
-  }
+  if (FD < 0) return;
+  flush();
+  if (ShouldClose)
+    if (::close(FD) != 0)
+      error_detected();
 }
 
+
 void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
   assert (FD >= 0 && "File already closed.");
   pos += Size;