Index: include/llvm/Support/Path.h
===================================================================
--- include/llvm/Support/Path.h
+++ include/llvm/Support/Path.h
@@ -295,6 +295,11 @@
 /// @result true if \a value is a path separator character on the host OS
 bool is_separator(char value);
 
+/// @brief Return the preferred separator for this platform.
+///
+/// @result const char* to the preferred separator, null-terminated.
+const char *get_separator();
+
 /// @brief Get the typical temporary directory for the system, e.g., 
 /// "/var/tmp" or "C:/TEMP"
 ///
Index: lib/MC/MCDwarf.cpp
===================================================================
--- lib/MC/MCDwarf.cpp
+++ lib/MC/MCDwarf.cpp
@@ -689,7 +689,7 @@
   const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
   if (MCDwarfDirs.size() > 0) {
     MCOS->EmitBytes(MCDwarfDirs[0]);
-    MCOS->EmitBytes("/");
+    MCOS->EmitBytes(sys::path::get_separator());
   }
   const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
     MCOS->getContext().getMCDwarfFiles();
Index: lib/Support/Path.cpp
===================================================================
--- lib/Support/Path.cpp
+++ lib/Support/Path.cpp
@@ -569,6 +569,12 @@
   }
 }
 
+static const char preferred_separator_string[] = { preferred_separator, '\0' };
+
+const char *get_separator() {
+  return preferred_separator_string;
+}
+
 void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result) {
   result.clear();
 
Index: lib/Support/SourceMgr.cpp
===================================================================
--- lib/Support/SourceMgr.cpp
+++ lib/Support/SourceMgr.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Locale.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/system_error.h"
 using namespace llvm;
@@ -60,7 +61,7 @@
 
   // If the file didn't exist directly, see if it's in an include path.
   for (unsigned i = 0, e = IncludeDirectories.size(); i != e && !NewBuf; ++i) {
-    IncludedFile = IncludeDirectories[i] + "/" + Filename;
+    IncludedFile = IncludeDirectories[i] + sys::path::get_separator() + Filename;
     MemoryBuffer::getFile(IncludedFile.c_str(), NewBuf);
   }