diff --git a/lib/Basic/FileManager.cpp b/lib/Basic/FileManager.cpp
index 488d4c3..921778d 100644
--- a/lib/Basic/FileManager.cpp
+++ b/lib/Basic/FileManager.cpp
@@ -392,10 +392,11 @@
 
 void FileManager::FixupRelativePath(llvm::sys::Path &path,
                                     const FileSystemOptions &FSOpts) {
-  if (FSOpts.WorkingDir.empty() || path.isAbsolute()) return;
-  
-  llvm::sys::Path NewPath(FSOpts.WorkingDir);
-  NewPath.appendComponent(path.str());
+  if (FSOpts.WorkingDir.empty() || llvm::sys::path::is_absolute(path.str()))
+    return;
+
+  llvm::SmallString<128> NewPath(FSOpts.WorkingDir);
+  llvm::sys::path::append(NewPath, path.str());
   path = NewPath;
 }
 
diff --git a/lib/Basic/FileSystemStatCache.cpp b/lib/Basic/FileSystemStatCache.cpp
index d9e89cd..c8b07af 100644
--- a/lib/Basic/FileSystemStatCache.cpp
+++ b/lib/Basic/FileSystemStatCache.cpp
@@ -113,7 +113,7 @@
     return Result;
   
   // Cache file 'stat' results and directories with absolutely paths.
-  if (!S_ISDIR(StatBuf.st_mode) || llvm::sys::Path(Path).isAbsolute())
+  if (!S_ISDIR(StatBuf.st_mode) || llvm::sys::path::is_absolute(Path))
     StatCalls[Path] = StatBuf;
   
   return Result;
diff --git a/lib/Checker/HTMLDiagnostics.cpp b/lib/Checker/HTMLDiagnostics.cpp
index c622369..b175fca 100644
--- a/lib/Checker/HTMLDiagnostics.cpp
+++ b/lib/Checker/HTMLDiagnostics.cpp
@@ -199,7 +199,7 @@
 
   std::string DirName = "";
 
-  if (!llvm::sys::Path(Entry->getName()).isAbsolute()) {
+  if (llvm::sys::path::is_relative(Entry->getName())) {
     llvm::sys::Path P = llvm::sys::Path::GetCurrentDirectory();
     DirName = P.str() + "/";
   }
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index 621ce8d..e021dcd 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -30,6 +30,7 @@
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Program.h"
 
@@ -757,14 +758,15 @@
 
       // Check that the file exists, if enabled.
       if (CheckInputsExist && memcmp(Value, "-", 2) != 0) {
-        llvm::sys::Path Path(Value);
+        llvm::SmallString<64> Path(Value);
         if (Arg *WorkDir = Args.getLastArg(options::OPT_working_directory))
-          if (!Path.isAbsolute()) {
+          if (llvm::sys::path::is_absolute(Path.str())) {
             Path = WorkDir->getValue(Args);
-            Path.appendComponent(Value);
+            llvm::sys::path::append(Path, Value);
           }
 
-        if (!Path.exists())
+        bool exists = false;
+        if (/*error_code ec =*/llvm::sys::fs::exists(Value, exists) || !exists)
           Diag(clang::diag::err_drv_no_such_file) << Path.str();
         else
           Inputs.push_back(std::make_pair(Ty, A));
diff --git a/lib/Frontend/CacheTokens.cpp b/lib/Frontend/CacheTokens.cpp
index ee8c8aa..cd5723a 100644
--- a/lib/Frontend/CacheTokens.cpp
+++ b/lib/Frontend/CacheTokens.cpp
@@ -475,8 +475,7 @@
     const FileEntry *FE = C.Entry;
 
     // FIXME: Handle files with non-absolute paths.
-    llvm::sys::Path P(FE->getName());
-    if (!P.isAbsolute())
+    if (llvm::sys::path::is_relative(FE->getName()))
       continue;
 
     const llvm::MemoryBuffer *B = C.getBuffer(PP.getDiagnostics(), SM);
@@ -525,7 +524,7 @@
       PM.insert(PTHEntryKeyVariant(Path), PTHEntry());
     else if (S_ISDIR(StatBuf.st_mode)) {
       // Only cache directories with absolute paths.
-      if (!llvm::sys::Path(Path).isAbsolute())
+      if (llvm::sys::path::is_relative(Path))
         return Result;
 
       PM.insert(PTHEntryKeyVariant(&StatBuf, Path), PTHEntry());
diff --git a/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
index 438556e..5bae3ea 100644
--- a/lib/Frontend/InitHeaderSearch.cpp
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -106,10 +106,10 @@
   // Compute the actual path, taking into consideration -isysroot.
   llvm::SmallString<256> MappedPathStorage;
   llvm::StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
-  llvm::sys::Path MappedPath(MappedPathStr);
 
   // Handle isysroot.
-  if (Group == System && !IgnoreSysRoot && MappedPath.isAbsolute() &&
+  if (Group == System && !IgnoreSysRoot &&
+      llvm::sys::path::is_absolute(MappedPathStr) &&
       IncludeSysroot != llvm::sys::Path::GetRootDirectory()) {
     MappedPathStorage.clear();
     MappedPathStr =
diff --git a/lib/Lex/HeaderSearch.cpp b/lib/Lex/HeaderSearch.cpp
index 6b74090..d11e87f 100644
--- a/lib/Lex/HeaderSearch.cpp
+++ b/lib/Lex/HeaderSearch.cpp
@@ -211,7 +211,7 @@
                                           const DirectoryLookup *&CurDir,
                                           const FileEntry *CurFileEnt) {
   // If 'Filename' is absolute, check to see if it exists and no searching.
-  if (llvm::sys::Path::isAbsolute(Filename.begin(), Filename.size())) {
+  if (llvm::sys::path::is_absolute(Filename)) {
     CurDir = 0;
 
     // If this was an #include_next "/absolute/file", fail.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index a4ba496..724ebdf 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1703,7 +1703,7 @@
   if (!RelocatablePCH)
     return;
 
-  if (Filename.empty() || llvm::sys::Path(Filename).isAbsolute())
+  if (Filename.empty() || llvm::sys::path::is_absolute(Filename))
     return;
 
   if (isysroot == 0) {