Index: llvm/trunk/lib/Support/Windows/DynamicLibrary.inc
===================================================================
--- llvm/trunk/lib/Support/Windows/DynamicLibrary.inc
+++ llvm/trunk/lib/Support/Windows/DynamicLibrary.inc
@@ -76,14 +76,14 @@
   SmallVector<wchar_t, MAX_PATH> filenameUnicode;
   if (std::error_code ec = windows::UTF8ToUTF16(filename, filenameUnicode)) {
     SetLastError(ec.value());
-    MakeErrMsg(errMsg, std::string(filename) + ": Can't convert to UTF-16: ");
+    MakeErrMsg(errMsg, std::string(filename) + ": Can't convert to UTF-16");
     return DynamicLibrary();
   }
   
   HMODULE a_handle = LoadLibraryW(filenameUnicode.data());
 
   if (a_handle == 0) {
-    MakeErrMsg(errMsg, std::string(filename) + ": Can't open : ");
+    MakeErrMsg(errMsg, std::string(filename) + ": Can't open");
     return DynamicLibrary();
   }
 
Index: llvm/trunk/lib/Support/Windows/Memory.inc
===================================================================
--- llvm/trunk/lib/Support/Windows/Memory.inc
+++ llvm/trunk/lib/Support/Windows/Memory.inc
@@ -192,14 +192,14 @@
 
 bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
   if (!setRangeWritable(M.Address, M.Size)) {
-    return MakeErrMsg(ErrMsg, "Cannot set memory to writeable: ");
+    return MakeErrMsg(ErrMsg, "Cannot set memory to writeable");
   }
   return true;
 }
 
 bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
   if (!setRangeExecutable(M.Address, M.Size)) {
-    return MakeErrMsg(ErrMsg, "Cannot set memory to executable: ");
+    return MakeErrMsg(ErrMsg, "Cannot set memory to executable");
   }
   return true;
 }
Index: llvm/trunk/lib/Support/Windows/Program.inc
===================================================================
--- llvm/trunk/lib/Support/Windows/Program.inc
+++ llvm/trunk/lib/Support/Windows/Program.inc
@@ -139,7 +139,7 @@
                   FILE_ATTRIBUTE_NORMAL, NULL);
   if (h == INVALID_HANDLE_VALUE) {
     MakeErrMsg(ErrMsg, fname + ": Can't open file for " +
-        (fd ? "input: " : "output: "));
+        (fd ? "input" : "output"));
   }
 
   return h;
@@ -431,7 +431,7 @@
     if (SecondsToWait) {
       if (!TerminateProcess(PI.ProcessHandle, 1)) {
         if (ErrMsg)
-          MakeErrMsg(ErrMsg, "Failed to terminate timed-out program.");
+          MakeErrMsg(ErrMsg, "Failed to terminate timed-out program");
 
         // -2 indicates a crash or timeout as opposed to failure to execute.
         WaitResult.ReturnCode = -2;
@@ -456,7 +456,7 @@
   if (!rc) {
     SetLastError(err);
     if (ErrMsg)
-      MakeErrMsg(ErrMsg, "Failed getting status for program.");
+      MakeErrMsg(ErrMsg, "Failed getting status for program");
 
     // -2 indicates a crash or timeout as opposed to failure to execute.
     WaitResult.ReturnCode = -2;
Index: llvm/trunk/lib/Support/Windows/WindowsSupport.h
===================================================================
--- llvm/trunk/lib/Support/Windows/WindowsSupport.h
+++ llvm/trunk/lib/Support/Windows/WindowsSupport.h
@@ -32,6 +32,7 @@
 #define WIN32_LEAN_AND_MEAN
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Config/config.h" // Get build system configuration settings
@@ -47,13 +48,16 @@
   if (!ErrMsg)
     return true;
   char *buffer = NULL;
+  DWORD LastError = GetLastError();
   DWORD R = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
-                          FORMAT_MESSAGE_FROM_SYSTEM,
-                          NULL, GetLastError(), 0, (LPSTR)&buffer, 1, NULL);
+                          FORMAT_MESSAGE_FROM_SYSTEM |
+                          FORMAT_MESSAGE_MAX_WIDTH_MASK,
+                          NULL, LastError, 0, (LPSTR)&buffer, 1, NULL);
   if (R)
-    *ErrMsg = prefix + buffer;
+    *ErrMsg = prefix + ": " + buffer;
   else
-    *ErrMsg = prefix + "Unknown error";
+    *ErrMsg = prefix + ": Unknown error";
+  *ErrMsg += " (0x" + llvm::utohexstr(LastError) + ")";
 
   LocalFree(buffer);
   return R != 0;