diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 45f2fe4..85eee54 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1399,6 +1399,7 @@
 if test "$llvm_cv_os_type" = "MingW" ; then
   AC_CHECK_LIB(imagehlp, main)
   AC_CHECK_LIB(psapi, main)
+  AC_CHECK_LIB(shell32, main)
 fi
 
 dnl dlopen() is required for plugin support.
diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 57725f8..dc991a2 100755
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -415,6 +415,7 @@
 if( MINGW )
   set(HAVE_LIBIMAGEHLP 1)
   set(HAVE_LIBPSAPI 1)
+  set(HAVE_LIBSHELL32 1)
   # TODO: Check existence of libraries.
   #   include(CheckLibraryExists)
   #   CHECK_LIBRARY_EXISTS(imagehlp ??? . HAVE_LIBIMAGEHLP)
diff --git a/cmake/modules/LLVM-Config.cmake b/cmake/modules/LLVM-Config.cmake
index 9fa45ce..e26fabd 100644
--- a/cmake/modules/LLVM-Config.cmake
+++ b/cmake/modules/LLVM-Config.cmake
@@ -2,7 +2,7 @@
   # Returns in `return_var' a list of system libraries used by LLVM.
   if( NOT MSVC )
     if( MINGW )
-      set(system_libs ${system_libs} imagehlp psapi)
+      set(system_libs ${system_libs} imagehlp psapi shell32)
     elseif( CMAKE_HOST_UNIX )
       if( HAVE_LIBRT )
         set(system_libs ${system_libs} rt)
diff --git a/cmake/modules/TableGen.cmake b/cmake/modules/TableGen.cmake
index bbd6339..c17e67e 100644
--- a/cmake/modules/TableGen.cmake
+++ b/cmake/modules/TableGen.cmake
@@ -128,7 +128,7 @@
   endif()
 
   if( MINGW )
-    target_link_libraries(${target} imagehlp psapi)
+    target_link_libraries(${target} imagehlp psapi shell32)
     if(CMAKE_SIZEOF_VOID_P MATCHES "8")
       set_target_properties(${target} PROPERTIES LINK_FLAGS -Wl,--stack,16777216)
     endif(CMAKE_SIZEOF_VOID_P MATCHES "8")
diff --git a/include/llvm/Config/config.h.cmake b/include/llvm/Config/config.h.cmake
index 77de967..4c49cbb 100644
--- a/include/llvm/Config/config.h.cmake
+++ b/include/llvm/Config/config.h.cmake
@@ -203,6 +203,9 @@
 /* Define to 1 if you have the `pthread' library (-lpthread). */
 #cmakedefine HAVE_LIBPTHREAD ${HAVE_LIBPTHREAD}
 
+/* Define to 1 if you have the `shell32' library (-lshell32). */
+#cmakedefine HAVE_LIBSHELL32 ${HAVE_LIBSHELL32}
+
 /* Define to 1 if you have the `udis86' library (-ludis86). */
 #undef HAVE_LIBUDIS86
 
diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index 860bccb..0d43ae5 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -217,6 +217,9 @@
 /* Define to 1 if you have the `pthread' library (-lpthread). */
 #undef HAVE_LIBPTHREAD
 
+/* Define to 1 if you have the `shell32' library (-lshell32). */
+#undef HAVE_LIBSHELL32
+
 /* Define to 1 if you have the `udis86' library (-ludis86). */
 #undef HAVE_LIBUDIS86
 
diff --git a/include/llvm/Support/Process.h b/include/llvm/Support/Process.h
index ce39d04..2172036 100644
--- a/include/llvm/Support/Process.h
+++ b/include/llvm/Support/Process.h
@@ -25,8 +25,11 @@
 #ifndef LLVM_SUPPORT_PROCESS_H
 #define LLVM_SUPPORT_PROCESS_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Config/llvm-config.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/system_error.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/TimeValue.h"
 
@@ -168,6 +171,14 @@
   // string. \arg Name is assumed to be in UTF-8 encoding too.
   static Optional<std::string> GetEnv(StringRef name);
 
+  /// This function returns a SmallVector containing the arguments passed from
+  /// the operating system to the program.  This function expects to be handed
+  /// the vector passed in from main.
+  static error_code
+  GetArgumentVector(SmallVectorImpl<const char *> &Args,
+                    ArrayRef<const char *> ArgsFromMain,
+                    SpecificBumpPtrAllocator<char> &ArgAllocator);
+
   /// This function determines if the standard input is connected directly
   /// to a user's input (keyboard probably), rather than coming from a file
   /// or pipe.
diff --git a/lib/Support/Unix/Process.inc b/lib/Support/Unix/Process.inc
index f18fa22..c5778e7 100644
--- a/lib/Support/Unix/Process.inc
+++ b/lib/Support/Unix/Process.inc
@@ -190,6 +190,14 @@
   return std::string(Val);
 }
 
+error_code Process::GetArgumentVector(SmallVectorImpl<const char *> &ArgsOut,
+                                      ArrayRef<const char *> ArgsIn,
+                                      SpecificBumpPtrAllocator<char> &) {
+  ArgsOut.append(ArgsIn.begin(), ArgsIn.end());
+
+  return error_code::success();
+}
+
 bool Process::StandardInIsUserInput() {
   return FileDescriptorIsDisplayed(STDIN_FILENO);
 }
diff --git a/lib/Support/Windows/DynamicLibrary.inc b/lib/Support/Windows/DynamicLibrary.inc
index 2edaf74..5a7b219 100644
--- a/lib/Support/Windows/DynamicLibrary.inc
+++ b/lib/Support/Windows/DynamicLibrary.inc
@@ -83,8 +83,15 @@
     // This is mostly to ensure that the return value still shows up as "valid".
     return DynamicLibrary(&OpenedHandles);
   }
+
+  SmallVector<wchar_t, MAX_PATH> filenameUnicode;
+  if (error_code ec = windows::UTF8ToUTF16(filename, filenameUnicode)) {
+    SetLastError(ec.value());
+    MakeErrMsg(errMsg, std::string(filename) + ": Can't convert to UTF-16: ");
+    return DynamicLibrary();
+  }
   
-  HMODULE a_handle = LoadLibrary(filename);
+  HMODULE a_handle = LoadLibraryW(filenameUnicode.data());
 
   if (a_handle == 0) {
     MakeErrMsg(errMsg, std::string(filename) + ": Can't open : ");
diff --git a/lib/Support/Windows/Path.inc b/lib/Support/Windows/Path.inc
index 94a501b..998ec42 100644
--- a/lib/Support/Windows/Path.inc
+++ b/lib/Support/Windows/Path.inc
@@ -128,7 +128,7 @@
       BYTE val = 0;
       if (!::CryptGenRandom(CryptoProvider, 1, &val))
           return windows_error(::GetLastError());
-      random_path_utf16.push_back("0123456789abcdef"[val & 15]);
+      random_path_utf16.push_back(L"0123456789abcdef"[val & 15]);
     }
     else
       random_path_utf16.push_back(*i);
@@ -241,22 +241,23 @@
 }
 
 error_code current_path(SmallVectorImpl<char> &result) {
-  SmallVector<wchar_t, 128> cur_path;
-  cur_path.reserve(128);
-retry_cur_dir:
-  DWORD len = ::GetCurrentDirectoryW(cur_path.capacity(), cur_path.data());
+  SmallVector<wchar_t, MAX_PATH> cur_path;
+  DWORD len = MAX_PATH;
 
-  // A zero return value indicates a failure other than insufficient space.
-  if (len == 0)
-    return windows_error(::GetLastError());
-
-  // If there's insufficient space, the len returned is larger than the len
-  // given.
-  if (len > cur_path.capacity()) {
+  do {
     cur_path.reserve(len);
-    goto retry_cur_dir;
-  }
+    len = ::GetCurrentDirectoryW(cur_path.capacity(), cur_path.data());
 
+    // A zero return value indicates a failure other than insufficient space.
+    if (len == 0)
+      return windows_error(::GetLastError());
+
+    // If there's insufficient space, the len returned is larger than the len
+    // given.
+  } while (len > cur_path.capacity());
+
+  // On success, GetCurrentDirectoryW returns the number of characters not
+  // including the null-terminator.
   cur_path.set_size(len);
   return UTF16ToUTF8(cur_path.begin(), cur_path.size(), result);
 }
diff --git a/lib/Support/Windows/Process.inc b/lib/Support/Windows/Process.inc
index 5d77650..7f7e06c 100644
--- a/lib/Support/Windows/Process.inc
+++ b/lib/Support/Windows/Process.inc
@@ -11,18 +11,25 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/Allocator.h"
+
 #include "Windows.h"
 #include <direct.h>
 #include <io.h>
 #include <malloc.h>
 #include <psapi.h>
+#include <Shellapi.h>
 
 #ifdef __MINGW32__
  #if (HAVE_LIBPSAPI != 1)
   #error "libpsapi.a should be present"
  #endif
+ #if (HAVE_LIBSHELL32 != 1)
+  #error "libshell32.a should be present"
+ #endif
 #else
- #pragma comment(lib, "psapi.lib")
+#pragma comment(lib, "psapi.lib")
+#pragma comment(lib, "Shell32.lib")
 #endif
 
 //===----------------------------------------------------------------------===//
@@ -151,25 +158,58 @@
   // Environment variable can be encoded in non-UTF8 encoding, and there's no
   // way to know what the encoding is. The only reliable way to look up
   // multibyte environment variable is to use GetEnvironmentVariableW().
-  std::vector<wchar_t> Buf(16);
-  size_t Size = 0;
-  for (;;) {
-    Size = GetEnvironmentVariableW(&NameUTF16[0], &Buf[0], Buf.size());
-    if (Size < Buf.size())
-      break;
+  SmallVector<wchar_t, MAX_PATH> Buf;
+  size_t Size = MAX_PATH;
+  do {
+    Buf.reserve(Size);
+    Size = GetEnvironmentVariableW(&NameUTF16[0], &Buf[0], Buf.capacity());
+    if (Size == 0)
+      return None;
+
     // Try again with larger buffer.
-    Buf.resize(Size + 1);
-  }
-  if (Size == 0)
-    return None;
+  } while (Size > Buf.capacity());
+  Buf.set_size(Size);
 
   // Convert the result from UTF-16 to UTF-8.
-  SmallVector<char, 128> Res;
+  SmallVector<char, MAX_PATH> Res;
   if (error_code ec = windows::UTF16ToUTF8(&Buf[0], Size, Res))
     return None;
   return std::string(&Res[0]);
 }
 
+error_code
+Process::GetArgumentVector(SmallVectorImpl<const char *> &Args,
+                           ArrayRef<const char *>,
+                           SpecificBumpPtrAllocator<char> &ArgAllocator) {
+  int NewArgCount;
+  error_code ec;
+
+  wchar_t **UnicodeCommandLine = CommandLineToArgvW(GetCommandLineW(),
+                                                    &NewArgCount);
+  if (!UnicodeCommandLine)
+    return windows_error(::GetLastError());
+
+  Args.reserve(NewArgCount);
+
+  for (int i = 0; i < NewArgCount; ++i) {
+    SmallVector<char, MAX_PATH> NewArgString;
+    ec = windows::UTF16ToUTF8(UnicodeCommandLine[i],
+                              wcslen(UnicodeCommandLine[i]),
+                              NewArgString);
+    if (ec)
+      break;
+
+    char *Buffer = ArgAllocator.Allocate(NewArgString.size() + 1);
+    ::memcpy(Buffer, NewArgString.data(), NewArgString.size() + 1);
+    Args.push_back(Buffer);
+  }
+  LocalFree(UnicodeCommandLine);
+  if (ec)
+    return ec;
+
+  return error_code::success();
+}
+
 bool Process::StandardInIsUserInput() {
   return FileDescriptorIsDisplayed(0);
 }
diff --git a/lib/Support/Windows/Program.inc b/lib/Support/Windows/Program.inc
index 2869085..e464e2f 100644
--- a/lib/Support/Windows/Program.inc
+++ b/lib/Support/Windows/Program.inc
@@ -42,42 +42,39 @@
 
   // At this point, the file name is valid and does not contain slashes.
   // Let Windows search for it.
-  std::string buffer;
-  buffer.resize(MAX_PATH);
-  char *dummy = NULL;
-  DWORD len = SearchPath(NULL, progName.c_str(), ".exe", MAX_PATH,
-                         &buffer[0], &dummy);
-
-  // See if it wasn't found.
-  if (len == 0)
+  SmallVector<wchar_t, MAX_PATH> progNameUnicode;
+  if (windows::UTF8ToUTF16(progName, progNameUnicode))
     return "";
 
-  // See if we got the entire path.
-  if (len < MAX_PATH)
-    return buffer;
+  SmallVector<wchar_t, MAX_PATH> buffer;
+  DWORD len = MAX_PATH;
+  do {
+    buffer.reserve(len);
+    len = ::SearchPathW(NULL, progNameUnicode.data(), L".exe",
+                        buffer.capacity(), buffer.data(), NULL);
 
-  // Buffer was too small; grow and retry.
-  while (true) {
-    buffer.resize(len+1);
-    DWORD len2 = SearchPath(NULL, progName.c_str(), ".exe", len+1, &buffer[0], &dummy);
-
-    // It is unlikely the search failed, but it's always possible some file
-    // was added or removed since the last search, so be paranoid...
-    if (len2 == 0)
+    // See if it wasn't found.
+    if (len == 0)
       return "";
-    else if (len2 <= len)
-      return buffer;
 
-    len = len2;
-  }
+    // Buffer was too small; grow and retry.
+  } while (len > buffer.capacity());
+
+  buffer.set_size(len);
+  SmallVector<char, MAX_PATH> result;
+  if (windows::UTF16ToUTF8(buffer.begin(), buffer.size(), result))
+    return "";
+
+  return std::string(result.data(), result.size());
 }
 
 static HANDLE RedirectIO(const StringRef *path, int fd, std::string* ErrMsg) {
   HANDLE h;
   if (path == 0) {
-    DuplicateHandle(GetCurrentProcess(), (HANDLE)_get_osfhandle(fd),
-                    GetCurrentProcess(), &h,
-                    0, TRUE, DUPLICATE_SAME_ACCESS);
+    if (!DuplicateHandle(GetCurrentProcess(), (HANDLE)_get_osfhandle(fd),
+                         GetCurrentProcess(), &h,
+                         0, TRUE, DUPLICATE_SAME_ACCESS))
+      return INVALID_HANDLE_VALUE;
     return h;
   }
 
@@ -92,9 +89,13 @@
   sa.lpSecurityDescriptor = 0;
   sa.bInheritHandle = TRUE;
 
-  h = CreateFile(fname.c_str(), fd ? GENERIC_WRITE : GENERIC_READ,
-                 FILE_SHARE_READ, &sa, fd == 0 ? OPEN_EXISTING : CREATE_ALWAYS,
-                 FILE_ATTRIBUTE_NORMAL, NULL);
+  SmallVector<wchar_t, 128> fnameUnicode;
+  if (windows::UTF8ToUTF16(fname, fnameUnicode))
+    return INVALID_HANDLE_VALUE;
+
+  h = CreateFileW(fnameUnicode.data(), fd ? GENERIC_WRITE : GENERIC_READ,
+                  FILE_SHARE_READ, &sa, fd == 0 ? OPEN_EXISTING : CREATE_ALWAYS,
+                  FILE_ATTRIBUTE_NORMAL, NULL);
   if (h == INVALID_HANDLE_VALUE) {
     MakeErrMsg(ErrMsg, std::string(fname) + ": Can't open file for " +
         (fd ? "input: " : "output: "));
@@ -218,34 +219,28 @@
   *p = 0;
 
   // The pointer to the environment block for the new process.
-  OwningArrayPtr<char> envblock;
+  std::vector<wchar_t> EnvBlock;
 
   if (envp) {
     // An environment block consists of a null-terminated block of
     // null-terminated strings. Convert the array of environment variables to
     // an environment block by concatenating them.
+    for (unsigned i = 0; envp[i]; ++i) {
+      SmallVector<wchar_t, MAX_PATH> EnvString;
+      if (error_code ec = windows::UTF8ToUTF16(envp[i], EnvString)) {
+        SetLastError(ec.value());
+        MakeErrMsg(ErrMsg, "Unable to convert environment variable to UTF-16");
+        return false;
+      }
 
-    // First, determine the length of the environment block.
-    len = 0;
-    for (unsigned i = 0; envp[i]; i++)
-      len += strlen(envp[i]) + 1;
-
-    // Now build the environment block.
-    envblock.reset(new char[len+1]);
-    p = envblock.get();
-
-    for (unsigned i = 0; envp[i]; i++) {
-      const char *ev = envp[i];
-      size_t len = strlen(ev) + 1;
-      memcpy(p, ev, len);
-      p += len;
+      EnvBlock.insert(EnvBlock.end(), EnvString.begin(), EnvString.end());
+      EnvBlock.push_back(0);
     }
-
-    *p = 0;
+    EnvBlock.push_back(0);
   }
 
   // Create a child process.
-  STARTUPINFO si;
+  STARTUPINFOW si;
   memset(&si, 0, sizeof(si));
   si.cb = sizeof(si);
   si.hStdInput = INVALID_HANDLE_VALUE;
@@ -269,9 +264,14 @@
     if (redirects[1] && redirects[2] && *(redirects[1]) == *(redirects[2])) {
       // If stdout and stderr should go to the same place, redirect stderr
       // to the handle already open for stdout.
-      DuplicateHandle(GetCurrentProcess(), si.hStdOutput,
-                      GetCurrentProcess(), &si.hStdError,
-                      0, TRUE, DUPLICATE_SAME_ACCESS);
+      if (!DuplicateHandle(GetCurrentProcess(), si.hStdOutput,
+                           GetCurrentProcess(), &si.hStdError,
+                           0, TRUE, DUPLICATE_SAME_ACCESS)) {
+        CloseHandle(si.hStdInput);
+        CloseHandle(si.hStdOutput);
+        MakeErrMsg(ErrMsg, "can't dup stderr to stdout");
+        return false;
+      }
     } else {
       // Just redirect stderr
       si.hStdError = RedirectIO(redirects[2], 2, ErrMsg);
@@ -289,9 +289,27 @@
 
   fflush(stdout);
   fflush(stderr);
-  std::string ProgramStr = Program;
-  BOOL rc = CreateProcess(ProgramStr.c_str(), command.get(), NULL, NULL, TRUE,
-                          0, envblock.get(), NULL, &si, &pi);
+
+  SmallVector<wchar_t, MAX_PATH> ProgramUtf16;
+  if (error_code ec = windows::UTF8ToUTF16(Program, ProgramUtf16)) {
+    SetLastError(ec.value());
+    MakeErrMsg(ErrMsg,
+               std::string("Unable to convert application name to UTF-16"));
+    return false;
+  }
+
+  SmallVector<wchar_t, MAX_PATH> CommandUtf16;
+  if (error_code ec = windows::UTF8ToUTF16(command.get(), CommandUtf16)) {
+    SetLastError(ec.value());
+    MakeErrMsg(ErrMsg,
+               std::string("Unable to convert command-line to UTF-16"));
+    return false;
+  }
+
+  BOOL rc = CreateProcessW(ProgramUtf16.data(), CommandUtf16.data(), 0, 0,
+                           TRUE, CREATE_UNICODE_ENVIRONMENT,
+                           EnvBlock.empty() ? 0 : EnvBlock.data(), 0, &si,
+                           &pi);
   DWORD err = GetLastError();
 
   // Regardless of whether the process got created or not, we are done with
@@ -304,7 +322,7 @@
   if (!rc) {
     SetLastError(err);
     MakeErrMsg(ErrMsg, std::string("Couldn't execute program '") +
-               ProgramStr + "'");
+               Program.str() + "'");
     return false;
   }
 
diff --git a/lib/Support/Windows/Signals.inc b/lib/Support/Windows/Signals.inc
index bce83b9..2b4a66d 100644
--- a/lib/Support/Windows/Signals.inc
+++ b/lib/Support/Windows/Signals.inc
@@ -135,7 +135,7 @@
 static fpSymFunctionTableAccess64 SymFunctionTableAccess64;
 
 static bool load64BitDebugHelp(void) {
-  HMODULE hLib = ::LoadLibrary("Dbghelp.dll");
+  HMODULE hLib = ::LoadLibrary(TEXT("Dbghelp.dll"));
   if (hLib) {
     StackWalk64 = (fpStackWalk64)
                       ::GetProcAddress(hLib, "StackWalk64");
diff --git a/lib/Support/Windows/Windows.h b/lib/Support/Windows/Windows.h
index 1236fe5..657ae4f 100644
--- a/lib/Support/Windows/Windows.h
+++ b/lib/Support/Windows/Windows.h
@@ -31,7 +31,6 @@
 #include "llvm/Support/system_error.h"
 #include <windows.h>
 #include <wincrypt.h>
-#include <shlobj.h>
 #include <cassert>
 #include <string>
 #include <vector>
diff --git a/projects/sample/autoconf/configure.ac b/projects/sample/autoconf/configure.ac
index 46fd549..03cd214 100644
--- a/projects/sample/autoconf/configure.ac
+++ b/projects/sample/autoconf/configure.ac
@@ -1087,6 +1087,7 @@
 if test "$llvm_cv_os_type" = "MingW" ; then
   AC_CHECK_LIB(imagehlp, main)
   AC_CHECK_LIB(psapi, main)
+  AC_CHECK_LIB(shell32, main)
 fi
 
 dnl dlopen() is required for plugin support.
diff --git a/utils/FileCheck/CMakeLists.txt b/utils/FileCheck/CMakeLists.txt
index fa56f92..d691ceb 100644
--- a/utils/FileCheck/CMakeLists.txt
+++ b/utils/FileCheck/CMakeLists.txt
@@ -4,7 +4,7 @@
 
 target_link_libraries(FileCheck LLVMSupport)
 if( MINGW )
-  target_link_libraries(FileCheck imagehlp psapi)
+  target_link_libraries(FileCheck imagehlp psapi shell32)
 endif( MINGW )
 if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
   target_link_libraries(FileCheck pthread)
diff --git a/utils/FileUpdate/CMakeLists.txt b/utils/FileUpdate/CMakeLists.txt
index 655aaec..0114e50 100644
--- a/utils/FileUpdate/CMakeLists.txt
+++ b/utils/FileUpdate/CMakeLists.txt
@@ -4,7 +4,7 @@
 
 target_link_libraries(FileUpdate LLVMSupport)
 if( MINGW )
-  target_link_libraries(FileUpdate imagehlp psapi)
+  target_link_libraries(FileUpdate imagehlp psapi shell32)
 endif( MINGW )
 if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
   target_link_libraries(FileUpdate pthread)
diff --git a/utils/not/CMakeLists.txt b/utils/not/CMakeLists.txt
index f4c0229..5ff14d6 100644
--- a/utils/not/CMakeLists.txt
+++ b/utils/not/CMakeLists.txt
@@ -4,7 +4,7 @@
 
 target_link_libraries(not LLVMSupport)
 if( MINGW )
-  target_link_libraries(not imagehlp psapi)
+  target_link_libraries(not imagehlp psapi shell32)
 endif( MINGW )
 if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
   target_link_libraries(not pthread)