Update the MemoryBuffer API to use ErrorOr.

llvm-svn: 212405

35 files changed, 297 insertions, 280 deletions

diff --git a/llvm/include/llvm/Support/MemoryBuffer.h b/llvm/include/llvm/Support/MemoryBuffer.h
index 8c742c6..147be47 100644
--- a/llvm/include/llvm/Support/MemoryBuffer.h
+++ b/llvm/include/llvm/Support/MemoryBuffer.h
@@ -19,6 +19,7 @@
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/ErrorOr.h"
 #include <memory>
 #include <system_error>
 
@@ -60,19 +61,17 @@ public:
     return "Unknown buffer";
   }
 
-  /// getFile - Open the specified file as a MemoryBuffer, returning a new
-  /// MemoryBuffer if successful, otherwise returning null.  If FileSize is
-  /// specified, this means that the client knows that the file exists and that
-  /// it has the specified size.
+  /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
+  /// if successful, otherwise returning null. If FileSize is specified, this
+  /// means that the client knows that the file exists and that it has the
+  /// specified size.
   ///
   /// \param IsVolatileSize Set to true to indicate that the file size may be
   /// changing, e.g. when libclang tries to parse while the user is
   /// editing/updating the file.
-  static std::error_code getFile(Twine Filename,
-                                 std::unique_ptr<MemoryBuffer> &Result,
-                                 int64_t FileSize = -1,
-                                 bool RequiresNullTerminator = true,
-                                 bool IsVolatileSize = false);
+  static ErrorOr<std::unique_ptr<MemoryBuffer>>
+  getFile(Twine Filename, int64_t FileSize = -1,
+          bool RequiresNullTerminator = true, bool IsVolatileSize = false);
 
   /// Given an already-open file descriptor, map some slice of it into a
   /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
@@ -81,10 +80,9 @@ public:
   /// \param IsVolatileSize Set to true to indicate that the file size may be
   /// changing, e.g. when libclang tries to parse while the user is
   /// editing/updating the file.
-  static std::error_code getOpenFileSlice(int FD, const char *Filename,
-                                          std::unique_ptr<MemoryBuffer> &Result,
-                                          uint64_t MapSize, int64_t Offset,
-                                          bool IsVolatileSize = false);
+  static ErrorOr<std::unique_ptr<MemoryBuffer>>
+  getOpenFileSlice(int FD, const char *Filename, uint64_t MapSize,
+                   int64_t Offset, bool IsVolatileSize = false);
 
   /// Given an already-open file descriptor, read the file and return a
   /// MemoryBuffer.
@@ -92,11 +90,9 @@ public:
   /// \param IsVolatileSize Set to true to indicate that the file size may be
   /// changing, e.g. when libclang tries to parse while the user is
   /// editing/updating the file.
-  static std::error_code getOpenFile(int FD, const char *Filename,
-                                     std::unique_ptr<MemoryBuffer> &Result,
-                                     uint64_t FileSize,
-                                     bool RequiresNullTerminator = true,
-                                     bool IsVolatileSize = false);
+  static ErrorOr<std::unique_ptr<MemoryBuffer>>
+  getOpenFile(int FD, const char *Filename, uint64_t FileSize,
+              bool RequiresNullTerminator = true, bool IsVolatileSize = false);
 
   /// getMemBuffer - Open the specified memory range as a MemoryBuffer.  Note
   /// that InputData must be null terminated if RequiresNullTerminator is true.
@@ -123,16 +119,13 @@ public:
   static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
                                              StringRef BufferName = "");
 
-  /// getSTDIN - Read all of stdin into a file buffer, and return it.
-  /// If an error occurs, this returns null and sets ec.
-  static std::error_code getSTDIN(std::unique_ptr<MemoryBuffer> &Result);
+  /// Read all of stdin into a file buffer, and return it.
+  static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN();
 
-  /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
-  /// if the Filename is "-".  If an error occurs, this returns null and sets
-  /// ec.
-  static std::error_code getFileOrSTDIN(StringRef Filename,
-                                        std::unique_ptr<MemoryBuffer> &Result,
-                                        int64_t FileSize = -1);
+  /// Open the specified file as a MemoryBuffer, or open stdin if the Filename
+  /// is "-".
+  static ErrorOr<std::unique_ptr<MemoryBuffer>>
+  getFileOrSTDIN(StringRef Filename, int64_t FileSize = -1);
 
   //===--------------------------------------------------------------------===//
   // Provided for performance analysis.
diff --git a/llvm/lib/AsmParser/Parser.cpp b/llvm/lib/AsmParser/Parser.cpp
index 2138fde..91bb51c 100644
--- a/llvm/lib/AsmParser/Parser.cpp
+++ b/llvm/lib/AsmParser/Parser.cpp
@@ -41,14 +41,15 @@ Module *llvm::ParseAssembly(MemoryBuffer *F,
 
 Module *llvm::ParseAssemblyFile(const std::string &Filename, SMDiagnostic &Err,
                                 LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, File)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (std::error_code EC = FileOrErr.getError()) {
     Err = SMDiagnostic(Filename, SourceMgr::DK_Error,
-                       "Could not open input file: " + ec.message());
+                       "Could not open input file: " + EC.message());
     return nullptr;
   }
 
-  return ParseAssembly(File.release(), nullptr, Err, Context);
+  return ParseAssembly(FileOrErr.get().release(), nullptr, Err, Context);
 }
 
 Module *llvm::ParseAssemblyString(const char *AsmString, Module *M,
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 0cb781c..87099a6 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -2606,28 +2606,24 @@ LLVMBool LLVMCreateMemoryBufferWithContentsOfFile(
     LLVMMemoryBufferRef *OutMemBuf,
     char **OutMessage) {
 
-  std::unique_ptr<MemoryBuffer> MB;
-  std::error_code ec;
-  if (!(ec = MemoryBuffer::getFile(Path, MB))) {
-    *OutMemBuf = wrap(MB.release());
-    return 0;
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr = MemoryBuffer::getFile(Path);
+  if (std::error_code EC = MBOrErr.getError()) {
+    *OutMessage = strdup(EC.message().c_str());
+    return 1;
   }
-
-  *OutMessage = strdup(ec.message().c_str());
-  return 1;
+  *OutMemBuf = wrap(MBOrErr.get().release());
+  return 0;
 }
 
 LLVMBool LLVMCreateMemoryBufferWithSTDIN(LLVMMemoryBufferRef *OutMemBuf,
                                          char **OutMessage) {
-  std::unique_ptr<MemoryBuffer> MB;
-  std::error_code ec;
-  if (!(ec = MemoryBuffer::getSTDIN(MB))) {
-    *OutMemBuf = wrap(MB.release());
-    return 0;
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr = MemoryBuffer::getSTDIN();
+  if (std::error_code EC = MBOrErr.getError()) {
+    *OutMessage = strdup(EC.message().c_str());
+    return 1;
   }
-
-  *OutMessage = strdup(ec.message().c_str());
-  return 1;
+  *OutMemBuf = wrap(MBOrErr.get().release());
+  return 0;
 }
 
 LLVMMemoryBufferRef LLVMCreateMemoryBufferWithMemoryRange(
diff --git a/llvm/lib/IR/GCOV.cpp b/llvm/lib/IR/GCOV.cpp
index b4c7977..1667401 100644
--- a/llvm/lib/IR/GCOV.cpp
+++ b/llvm/lib/IR/GCOV.cpp
@@ -438,11 +438,15 @@ class LineConsumer {
   StringRef Remaining;
 public:
   LineConsumer(StringRef Filename) {
-    if (std::error_code EC = MemoryBuffer::getFileOrSTDIN(Filename, Buffer)) {
+    ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+        MemoryBuffer::getFileOrSTDIN(Filename);
+    if (std::error_code EC = BufferOrErr.getError()) {
       errs() << Filename << ": " << EC.message() << "\n";
       Remaining = "";
-    } else
+    } else {
+      Buffer = std::move(BufferOrErr.get());
       Remaining = Buffer->getBuffer();
+    }
   }
   bool empty() { return Remaining.empty(); }
   void printNext(raw_ostream &OS, uint32_t LineNum) {
diff --git a/llvm/lib/IRReader/IRReader.cpp b/llvm/lib/IRReader/IRReader.cpp
index 00c6c0db..f8d2f5a 100644
--- a/llvm/lib/IRReader/IRReader.cpp
+++ b/llvm/lib/IRReader/IRReader.cpp
@@ -51,14 +51,15 @@ static Module *getLazyIRModule(MemoryBuffer *Buffer, SMDiagnostic &Err,
 
 Module *llvm::getLazyIRFileModule(const std::string &Filename, SMDiagnostic &Err,
                                   LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, File)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (std::error_code EC = FileOrErr.getError()) {
     Err = SMDiagnostic(Filename, SourceMgr::DK_Error,
-                       "Could not open input file: " + ec.message());
+                       "Could not open input file: " + EC.message());
     return nullptr;
   }
 
-  return getLazyIRModule(File.release(), Err, Context);
+  return getLazyIRModule(FileOrErr.get().release(), Err, Context);
 }
 
 Module *llvm::ParseIR(MemoryBuffer *Buffer, SMDiagnostic &Err,
@@ -85,14 +86,15 @@ Module *llvm::ParseIR(MemoryBuffer *Buffer, SMDiagnostic &Err,
 
 Module *llvm::ParseIRFile(const std::string &Filename, SMDiagnostic &Err,
                           LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, File)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (std::error_code EC = FileOrErr.getError()) {
     Err = SMDiagnostic(Filename, SourceMgr::DK_Error,
-                       "Could not open input file: " + ec.message());
+                       "Could not open input file: " + EC.message());
     return nullptr;
   }
 
-  return ParseIR(File.get(), Err, Context);
+  return ParseIR(FileOrErr.get().get(), Err, Context);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index 4b51166..335197a 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -236,13 +236,14 @@ const void* LTOCodeGenerator::compile(size_t* length,
   delete NativeObjectFile;
 
   // read .o file into memory buffer
-  std::unique_ptr<MemoryBuffer> BuffPtr;
-  if (std::error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
-    errMsg = ec.message();
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFile(name, -1, false);
+  if (std::error_code EC = BufferOrErr.getError()) {
+    errMsg = EC.message();
     sys::fs::remove(NativeObjectPath);
     return nullptr;
   }
-  NativeObjectFile = BuffPtr.release();
+  NativeObjectFile = BufferOrErr.get().release();
 
   // remove temp files
   sys::fs::remove(NativeObjectPath);
diff --git a/llvm/lib/LTO/LTOModule.cpp b/llvm/lib/LTO/LTOModule.cpp
index 5b3057177..844c0f2 100644
--- a/llvm/lib/LTO/LTOModule.cpp
+++ b/llvm/lib/LTO/LTOModule.cpp
@@ -69,12 +69,13 @@ bool LTOModule::isBitcodeForTarget(MemoryBuffer *buffer,
 
 LTOModule *LTOModule::createFromFile(const char *path, TargetOptions options,
                                      std::string &errMsg) {
-  std::unique_ptr<MemoryBuffer> buffer;
-  if (std::error_code ec = MemoryBuffer::getFile(path, buffer)) {
-    errMsg = ec.message();
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFile(path);
+  if (std::error_code EC = BufferOrErr.getError()) {
+    errMsg = EC.message();
     return nullptr;
   }
-  return makeLTOModule(std::move(buffer), options, errMsg);
+  return makeLTOModule(std::move(BufferOrErr.get()), options, errMsg);
 }
 
 LTOModule *LTOModule::createFromOpenFile(int fd, const char *path, size_t size,
@@ -87,13 +88,13 @@ LTOModule *LTOModule::createFromOpenFileSlice(int fd, const char *path,
                                               size_t map_size, off_t offset,
                                               TargetOptions options,
                                               std::string &errMsg) {
-  std::unique_ptr<MemoryBuffer> buffer;
-  if (std::error_code ec =
-          MemoryBuffer::getOpenFileSlice(fd, path, buffer, map_size, offset)) {
-    errMsg = ec.message();
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getOpenFileSlice(fd, path, map_size, offset);
+  if (std::error_code EC = BufferOrErr.getError()) {
+    errMsg = EC.message();
     return nullptr;
   }
-  return makeLTOModule(std::move(buffer), options, errMsg);
+  return makeLTOModule(std::move(BufferOrErr.get()), options, errMsg);
 }
 
 LTOModule *LTOModule::createFromBuffer(const void *mem, size_t length,
diff --git a/llvm/lib/Object/Binary.cpp b/llvm/lib/Object/Binary.cpp
index 8d79a96..9f6a685 100644
--- a/llvm/lib/Object/Binary.cpp
+++ b/llvm/lib/Object/Binary.cpp
@@ -75,8 +75,9 @@ ErrorOr<Binary *> object::createBinary(std::unique_ptr<MemoryBuffer> &Buffer,
 }
 
 ErrorOr<Binary *> object::createBinary(StringRef Path) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code EC = MemoryBuffer::getFileOrSTDIN(Path, File))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(Path);
+  if (std::error_code EC = FileOrErr.getError())
     return EC;
-  return createBinary(File);
+  return createBinary(FileOrErr.get());
 }
diff --git a/llvm/lib/Object/ObjectFile.cpp b/llvm/lib/Object/ObjectFile.cpp
index 591ed28..f5488c6 100644
--- a/llvm/lib/Object/ObjectFile.cpp
+++ b/llvm/lib/Object/ObjectFile.cpp
@@ -83,8 +83,9 @@ ObjectFile::createObjectFile(std::unique_ptr<MemoryBuffer> &Object,
 }
 
 ErrorOr<ObjectFile *> ObjectFile::createObjectFile(StringRef ObjectPath) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code EC = MemoryBuffer::getFile(ObjectPath, File))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFile(ObjectPath);
+  if (std::error_code EC = FileOrErr.getError())
     return EC;
-  return createObjectFile(File);
+  return createObjectFile(FileOrErr.get());
 }
diff --git a/llvm/lib/ProfileData/InstrProfReader.cpp b/llvm/lib/ProfileData/InstrProfReader.cpp
index d0493d3..0b36728 100644
--- a/llvm/lib/ProfileData/InstrProfReader.cpp
+++ b/llvm/lib/ProfileData/InstrProfReader.cpp
@@ -23,8 +23,11 @@ using namespace llvm;
 
 static std::error_code
 setupMemoryBuffer(std::string Path, std::unique_ptr<MemoryBuffer> &Buffer) {
-  if (std::error_code EC = MemoryBuffer::getFileOrSTDIN(Path, Buffer))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFileOrSTDIN(Path);
+  if (std::error_code EC = BufferOrErr.getError())
     return EC;
+  Buffer = std::move(BufferOrErr.get());
 
   // Sanity check the file.
   if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max())
diff --git a/llvm/lib/Support/CommandLine.cpp b/llvm/lib/Support/CommandLine.cpp
index c2b739f..87348f7 100644
--- a/llvm/lib/Support/CommandLine.cpp
+++ b/llvm/lib/Support/CommandLine.cpp
@@ -631,9 +631,11 @@ void cl::TokenizeWindowsCommandLine(StringRef Src, StringSaver &Saver,
 static bool ExpandResponseFile(const char *FName, StringSaver &Saver,
                                TokenizerCallback Tokenizer,
                                SmallVectorImpl<const char *> &NewArgv) {
-  std::unique_ptr<MemoryBuffer> MemBuf;
-  if (MemoryBuffer::getFile(FName, MemBuf))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MemBufOrErr =
+      MemoryBuffer::getFile(FName);
+  if (!MemBufOrErr)
     return false;
+  std::unique_ptr<MemoryBuffer> MemBuf = std::move(MemBufOrErr.get());
   StringRef Str(MemBuf->getBufferStart(), MemBuf->getBufferSize());
 
   // If we have a UTF-16 byte order mark, convert to UTF-8 for parsing.
diff --git a/llvm/lib/Support/FileUtilities.cpp b/llvm/lib/Support/FileUtilities.cpp
index 0d26baf..8a23491 100644
--- a/llvm/lib/Support/FileUtilities.cpp
+++ b/llvm/lib/Support/FileUtilities.cpp
@@ -176,18 +176,21 @@ int llvm::DiffFilesWithTolerance(StringRef NameA,
                                  std::string *Error) {
   // Now its safe to mmap the files into memory because both files
   // have a non-zero size.
-  std::unique_ptr<MemoryBuffer> F1;
-  if (std::error_code ec = MemoryBuffer::getFile(NameA, F1)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> F1OrErr = MemoryBuffer::getFile(NameA);
+  if (std::error_code EC = F1OrErr.getError()) {
     if (Error)
-      *Error = ec.message();
+      *Error = EC.message();
     return 2;
   }
-  std::unique_ptr<MemoryBuffer> F2;
-  if (std::error_code ec = MemoryBuffer::getFile(NameB, F2)) {
+  std::unique_ptr<MemoryBuffer> F1 = std::move(F1OrErr.get());
+
+  ErrorOr<std::unique_ptr<MemoryBuffer>> F2OrErr = MemoryBuffer::getFile(NameB);
+  if (std::error_code EC = F2OrErr.getError()) {
     if (Error)
-      *Error = ec.message();
+      *Error = EC.message();
     return 2;
   }
+  std::unique_ptr<MemoryBuffer> F2 = std::move(F2OrErr.get());
 
   // Okay, now that we opened the files, scan them for the first difference.
   const char *File1Start = F1->getBufferStart();
diff --git a/llvm/lib/Support/LockFileManager.cpp b/llvm/lib/Support/LockFileManager.cpp
index 681bae2..3f224e0 100644
--- a/llvm/lib/Support/LockFileManager.cpp
+++ b/llvm/lib/Support/LockFileManager.cpp
@@ -33,11 +33,13 @@ Optional<std::pair<std::string, int> >
 LockFileManager::readLockFile(StringRef LockFileName) {
   // Read the owning host and PID out of the lock file. If it appears that the
   // owning process is dead, the lock file is invalid.
-  std::unique_ptr<MemoryBuffer> MB;
-  if (MemoryBuffer::getFile(LockFileName, MB)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+      MemoryBuffer::getFile(LockFileName);
+  if (!MBOrErr) {
     sys::fs::remove(LockFileName);
     return None;
   }
+  std::unique_ptr<MemoryBuffer> MB = std::move(MBOrErr.get());
 
   StringRef Hostname;
   StringRef PIDStr;
diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index abf4f60..5f4b7da 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -152,18 +152,11 @@ MemoryBuffer *MemoryBuffer::getNewMemBuffer(size_t Size, StringRef BufferName) {
   return SB;
 }
 
-
-/// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
-/// if the Filename is "-".  If an error occurs, this returns null and fills
-/// in *ErrStr with a reason.  If stdin is empty, this API (unlike getSTDIN)
-/// returns an empty buffer.
-std::error_code
-MemoryBuffer::getFileOrSTDIN(StringRef Filename,
-                             std::unique_ptr<MemoryBuffer> &Result,
-                             int64_t FileSize) {
+ErrorOr<std::unique_ptr<MemoryBuffer>>
+MemoryBuffer::getFileOrSTDIN(StringRef Filename, int64_t FileSize) {
   if (Filename == "-")
-    return getSTDIN(Result);
-  return getFile(Filename, Result, FileSize);
+    return getSTDIN();
+  return getFile(Filename, FileSize);
 }
 
 
@@ -212,9 +205,8 @@ public:
 };
 }
 
-static std::error_code
-getMemoryBufferForStream(int FD, StringRef BufferName,
-                         std::unique_ptr<MemoryBuffer> &Result) {
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+getMemoryBufferForStream(int FD, StringRef BufferName) {
   const ssize_t ChunkSize = 4096*4;
   SmallString<ChunkSize> Buffer;
   ssize_t ReadBytes;
@@ -229,48 +221,43 @@ getMemoryBufferForStream(int FD, StringRef BufferName,
     Buffer.set_size(Buffer.size() + ReadBytes);
   } while (ReadBytes != 0);
 
-  Result.reset(MemoryBuffer::getMemBufferCopy(Buffer, BufferName));
-  return std::error_code();
+  std::unique_ptr<MemoryBuffer> Ret(
+      MemoryBuffer::getMemBufferCopy(Buffer, BufferName));
+  return std::move(Ret);
 }
 
-static std::error_code getFileAux(const char *Filename,
-                                  std::unique_ptr<MemoryBuffer> &Result,
-                                  int64_t FileSize, bool RequiresNullTerminator,
-                                  bool IsVolatileSize);
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+getFileAux(const char *Filename, int64_t FileSize, bool RequiresNullTerminator,
+           bool IsVolatileSize);
 
-std::error_code MemoryBuffer::getFile(Twine Filename,
-                                      std::unique_ptr<MemoryBuffer> &Result,
-                                      int64_t FileSize,
-                                      bool RequiresNullTerminator,
-                                      bool IsVolatileSize) {
+ErrorOr<std::unique_ptr<MemoryBuffer>>
+MemoryBuffer::getFile(Twine Filename, int64_t FileSize,
+                      bool RequiresNullTerminator, bool IsVolatileSize) {
   // Ensure the path is null terminated.
   SmallString<256> PathBuf;
   StringRef NullTerminatedName = Filename.toNullTerminatedStringRef(PathBuf);
-  return getFileAux(NullTerminatedName.data(), Result, FileSize,
-                    RequiresNullTerminator, IsVolatileSize);
+  return getFileAux(NullTerminatedName.data(), FileSize, RequiresNullTerminator,
+                    IsVolatileSize);
 }
 
-static std::error_code getOpenFileImpl(int FD, const char *Filename,
-                                       std::unique_ptr<MemoryBuffer> &Result,
-                                       uint64_t FileSize, uint64_t MapSize,
-                                       int64_t Offset,
-                                       bool RequiresNullTerminator,
-                                       bool IsVolatileSize);
-
-static std::error_code getFileAux(const char *Filename,
-                                  std::unique_ptr<MemoryBuffer> &Result,
-                                  int64_t FileSize, bool RequiresNullTerminator,
-                                  bool IsVolatileSize) {
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+getOpenFileImpl(int FD, const char *Filename, uint64_t FileSize,
+                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
+                bool IsVolatileSize);
+
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+getFileAux(const char *Filename, int64_t FileSize, bool RequiresNullTerminator,
+           bool IsVolatileSize) {
   int FD;
   std::error_code EC = sys::fs::openFileForRead(Filename, FD);
   if (EC)
     return EC;
 
-  std::error_code ret =
-      getOpenFileImpl(FD, Filename, Result, FileSize, FileSize, 0,
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Ret =
+      getOpenFileImpl(FD, Filename, FileSize, FileSize, 0,
                       RequiresNullTerminator, IsVolatileSize);
   close(FD);
-  return ret;
+  return Ret;
 }
 
 static bool shouldUseMmap(int FD,
@@ -321,12 +308,10 @@ static bool shouldUseMmap(int FD,
   return true;
 }
 
-static std::error_code getOpenFileImpl(int FD, const char *Filename,
-                                       std::unique_ptr<MemoryBuffer> &Result,
-                                       uint64_t FileSize, uint64_t MapSize,
-                                       int64_t Offset,
-                                       bool RequiresNullTerminator,
-                                       bool IsVolatileSize) {
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+getOpenFileImpl(int FD, const char *Filename, uint64_t FileSize,
+                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
+                bool IsVolatileSize) {
   static int PageSize = sys::process::get_self()->page_size();
 
   // Default is to map the full file.
@@ -345,7 +330,7 @@ static std::error_code getOpenFileImpl(int FD, const char *Filename,
       sys::fs::file_type Type = Status.type();
       if (Type != sys::fs::file_type::regular_file &&
           Type != sys::fs::file_type::block_file)
-        return getMemoryBufferForStream(FD, Filename, Result);
+        return getMemoryBufferForStream(FD, Filename);
 
       FileSize = Status.getSize();
     }
@@ -355,10 +340,11 @@ static std::error_code getOpenFileImpl(int FD, const char *Filename,
   if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
                     PageSize, IsVolatileSize)) {
     std::error_code EC;
-    Result.reset(new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile(
-        RequiresNullTerminator, FD, MapSize, Offset, EC));
+    std::unique_ptr<MemoryBuffer> Result(
+        new (NamedBufferAlloc(Filename))
+        MemoryBufferMMapFile(RequiresNullTerminator, FD, MapSize, Offset, EC));
     if (!EC)
-      return std::error_code();
+      return std::move(Result);
   }
 
   MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(MapSize, Filename);
@@ -397,36 +383,29 @@ static std::error_code getOpenFileImpl(int FD, const char *Filename,
     BufPtr += NumRead;
   }
 
-  Result.swap(SB);
-  return std::error_code();
+  return std::move(SB);
 }
 
-std::error_code MemoryBuffer::getOpenFile(int FD, const char *Filename,
-                                          std::unique_ptr<MemoryBuffer> &Result,
-                                          uint64_t FileSize,
-                                          bool RequiresNullTerminator,
-                                          bool IsVolatileSize) {
-  return getOpenFileImpl(FD, Filename, Result, FileSize, FileSize, 0,
+ErrorOr<std::unique_ptr<MemoryBuffer>>
+MemoryBuffer::getOpenFile(int FD, const char *Filename, uint64_t FileSize,
+                          bool RequiresNullTerminator, bool IsVolatileSize) {
+  return getOpenFileImpl(FD, Filename, FileSize, FileSize, 0,
                          RequiresNullTerminator, IsVolatileSize);
 }
 
-std::error_code MemoryBuffer::getOpenFileSlice(
-    int FD, const char *Filename, std::unique_ptr<MemoryBuffer> &Result,
-    uint64_t MapSize, int64_t Offset, bool IsVolatileSize) {
-  return getOpenFileImpl(FD, Filename, Result, -1, MapSize, Offset, false,
+ErrorOr<std::unique_ptr<MemoryBuffer>>
+MemoryBuffer::getOpenFileSlice(int FD, const char *Filename, uint64_t MapSize,
+                               int64_t Offset, bool IsVolatileSize) {
+  return getOpenFileImpl(FD, Filename, -1, MapSize, Offset, false,
                          IsVolatileSize);
 }
 
-//===----------------------------------------------------------------------===//
-// MemoryBuffer::getSTDIN implementation.
-//===----------------------------------------------------------------------===//
-
-std::error_code MemoryBuffer::getSTDIN(std::unique_ptr<MemoryBuffer> &Result) {
+ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
   // Read in all of the data from stdin, we cannot mmap stdin.
   //
   // FIXME: That isn't necessarily true, we should try to mmap stdin and
   // fallback if it fails.
   sys::ChangeStdinToBinary();
 
-  return getMemoryBufferForStream(0, "<stdin>", Result);
+  return getMemoryBufferForStream(0, "<stdin>");
 }
diff --git a/llvm/lib/Support/SourceMgr.cpp b/llvm/lib/Support/SourceMgr.cpp
index a9323d0..595c6ee 100644
--- a/llvm/lib/Support/SourceMgr.cpp
+++ b/llvm/lib/Support/SourceMgr.cpp
@@ -52,20 +52,22 @@ SourceMgr::~SourceMgr() {
 size_t SourceMgr::AddIncludeFile(const std::string &Filename,
                                  SMLoc IncludeLoc,
                                  std::string &IncludedFile) {
-  std::unique_ptr<MemoryBuffer> NewBuf;
   IncludedFile = Filename;
-  MemoryBuffer::getFile(IncludedFile.c_str(), NewBuf);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> NewBufOrErr =
+      MemoryBuffer::getFile(IncludedFile.c_str());
 
   // 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] + sys::path::get_separator().data() + Filename;
-    MemoryBuffer::getFile(IncludedFile.c_str(), NewBuf);
+  for (unsigned i = 0, e = IncludeDirectories.size(); i != e && !NewBufOrErr;
+       ++i) {
+    IncludedFile =
+        IncludeDirectories[i] + sys::path::get_separator().data() + Filename;
+    NewBufOrErr = MemoryBuffer::getFile(IncludedFile.c_str());
   }
 
-  if (!NewBuf)
+  if (!NewBufOrErr)
     return 0;
 
-  return AddNewSourceBuffer(NewBuf.release(), IncludeLoc);
+  return AddNewSourceBuffer(NewBufOrErr.get().release(), IncludeLoc);
 }
 
 unsigned SourceMgr::FindBufferContainingLoc(SMLoc Loc) const {
diff --git a/llvm/lib/TableGen/Main.cpp b/llvm/lib/TableGen/Main.cpp
index 191307a..e317fbf 100644
--- a/llvm/lib/TableGen/Main.cpp
+++ b/llvm/lib/TableGen/Main.cpp
@@ -81,13 +81,14 @@ int TableGenMain(char *argv0, TableGenMainFn *MainFn) {
   RecordKeeper Records;
 
   // Parse the input file.
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename, File)) {
-    errs() << "Could not open input file '" << InputFilename << "': "
-           << ec.message() <<"\n";
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(InputFilename);
+  if (std::error_code EC = FileOrErr.getError()) {
+    errs() << "Could not open input file '" << InputFilename
+           << "': " << EC.message() << "\n";
     return 1;
   }
-  MemoryBuffer *F = File.release();
+  MemoryBuffer *F = FileOrErr.get().release();
 
   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
   SrcMgr.AddNewSourceBuffer(F, SMLoc());
diff --git a/llvm/lib/Transforms/Scalar/SampleProfile.cpp b/llvm/lib/Transforms/Scalar/SampleProfile.cpp
index 888e252..73c97ff 100644
--- a/llvm/lib/Transforms/Scalar/SampleProfile.cpp
+++ b/llvm/lib/Transforms/Scalar/SampleProfile.cpp
@@ -450,13 +450,14 @@ void SampleModuleProfile::dump() {
 ///
 /// \returns true if the file was loaded successfully, false otherwise.
 bool SampleModuleProfile::loadText() {
-  std::unique_ptr<MemoryBuffer> Buffer;
-  std::error_code EC = MemoryBuffer::getFile(Filename, Buffer);
-  if (EC) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFile(Filename);
+  if (std::error_code EC = BufferOrErr.getError()) {
     std::string Msg(EC.message());
     M.getContext().diagnose(DiagnosticInfoSampleProfile(Filename.data(), Msg));
     return false;
   }
+  std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrErr.get());
   line_iterator LineIt(*Buffer, '#');
 
   // Read the profile of each function. Since each function may be
diff --git a/llvm/lib/Transforms/Utils/SpecialCaseList.cpp b/llvm/lib/Transforms/Utils/SpecialCaseList.cpp
index 45a2b61..3d76a17 100644
--- a/llvm/lib/Transforms/Utils/SpecialCaseList.cpp
+++ b/llvm/lib/Transforms/Utils/SpecialCaseList.cpp
@@ -54,12 +54,13 @@ SpecialCaseList *SpecialCaseList::create(
     const StringRef Path, std::string &Error) {
   if (Path.empty())
     return new SpecialCaseList();
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code EC = MemoryBuffer::getFile(Path, File)) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFile(Path);
+  if (std::error_code EC = FileOrErr.getError()) {
     Error = (Twine("Can't open file '") + Path + "': " + EC.message()).str();
     return nullptr;
   }
-  return create(File.get(), Error);
+  return create(FileOrErr.get().get(), Error);
 }
 
 SpecialCaseList *SpecialCaseList::create(
diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index 6d52f62..f424e46 100644
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -280,11 +280,14 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
     if (file->offset) {
       offset = file->offset;
     }
-    if (std::error_code ec = MemoryBuffer::getOpenFileSlice(
-            file->fd, file->name, buffer, file->filesize, offset)) {
-      (*message)(LDPL_ERROR, ec.message().c_str());
+    ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+        MemoryBuffer::getOpenFileSlice(file->fd, file->name, file->filesize,
+                                       offset);
+    if (std::error_code EC = BufferOrErr.getError()) {
+      (*message)(LDPL_ERROR, EC.message().c_str());
       return LDPS_ERR;
     }
+    buffer = std::move(BufferOrErr.get());
     view = buffer->getBufferStart();
   }
 
diff --git a/llvm/tools/lli/lli.cpp b/llvm/tools/lli/lli.cpp
index f69fb43..48828c1 100644
--- a/llvm/tools/lli/lli.cpp
+++ b/llvm/tools/lli/lli.cpp
@@ -285,8 +285,8 @@ public:
     if (!getCacheFilename(ModuleID, CacheName))
       return nullptr;
     // Load the object from the cache filename
-    std::unique_ptr<MemoryBuffer> IRObjectBuffer;
-    MemoryBuffer::getFile(CacheName.c_str(), IRObjectBuffer, -1, false);
+    ErrorOr<std::unique_ptr<MemoryBuffer>> IRObjectBuffer =
+        MemoryBuffer::getFile(CacheName.c_str(), -1, false);
     // If the file isn't there, that's OK.
     if (!IRObjectBuffer)
       return nullptr;
@@ -294,7 +294,7 @@ public:
     // because the file has probably just been mmapped.  Instead we make
     // a copy.  The filed-based buffer will be released when it goes
     // out of scope.
-    return MemoryBuffer::getMemBufferCopy(IRObjectBuffer->getBuffer());
+    return MemoryBuffer::getMemBufferCopy(IRObjectBuffer.get()->getBuffer());
   }
 
 private:
@@ -538,15 +538,15 @@ int main(int argc, char **argv, char * const *envp) {
   }
 
   for (unsigned i = 0, e = ExtraArchives.size(); i != e; ++i) {
-    std::unique_ptr<MemoryBuffer> ArBuf;
-    std::error_code ec;
-    ec = MemoryBuffer::getFileOrSTDIN(ExtraArchives[i], ArBuf);
-    if (ec) {
+    ErrorOr<std::unique_ptr<MemoryBuffer>> ArBuf =
+        MemoryBuffer::getFileOrSTDIN(ExtraArchives[i]);
+    if (!ArBuf) {
       Err.print(argv[0], errs());
       return 1;
     }
-    object::Archive *Ar = new object::Archive(std::move(ArBuf), ec);
-    if (ec || !Ar) {
+    std::error_code EC;
+    object::Archive *Ar = new object::Archive(std::move(ArBuf.get()), EC);
+    if (EC || !Ar) {
       Err.print(argv[0], errs());
       return 1;
     }
diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
index 4bd586b..f638e55 100644
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -770,10 +770,10 @@ static void performWriteOperation(ArchiveOperation Operation,
       const char *Filename = Member.getNew();
       int FD = Member.getFD();
       const sys::fs::file_status &Status = Member.getStatus();
-      failIfError(MemoryBuffer::getOpenFile(FD, Filename, MemberBuffer,
-                                            Status.getSize(), false),
-                  Filename);
-
+      ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
+          MemoryBuffer::getOpenFile(FD, Filename, Status.getSize(), false);
+      failIfError(MemberBufferOrErr.getError(), Filename);
+      MemberBuffer = std::move(MemberBufferOrErr.get());
     } else {
       object::Archive::child_iterator OldMember = Member.getOld();
       ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
@@ -934,8 +934,9 @@ int ar_main(char **argv) {
 
 static int performOperation(ArchiveOperation Operation) {
   // Create or open the archive object.
-  std::unique_ptr<MemoryBuffer> Buf;
-  std::error_code EC = MemoryBuffer::getFile(ArchiveName, Buf, -1, false);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
+      MemoryBuffer::getFile(ArchiveName, -1, false);
+  std::error_code EC = Buf.getError();
   if (EC && EC != errc::no_such_file_or_directory) {
     errs() << ToolName << ": error opening '" << ArchiveName
            << "': " << EC.message() << "!\n";
@@ -943,7 +944,7 @@ static int performOperation(ArchiveOperation Operation) {
   }
 
   if (!EC) {
-    object::Archive Archive(std::move(Buf), EC);
+    object::Archive Archive(std::move(Buf.get()), EC);
 
     if (EC) {
       errs() << ToolName << ": error loading '" << ArchiveName
diff --git a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
index fe2b235..15567cf 100644
--- a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
+++ b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
@@ -478,10 +478,11 @@ static void PrintSize(uint64_t Bits) {
 /// AnalyzeBitcode - Analyze the bitcode file specified by InputFilename.
 static int AnalyzeBitcode() {
   // Read the input file.
-  std::unique_ptr<MemoryBuffer> MemBuf;
-
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename, MemBuf))
-    return Error("Error reading '" + InputFilename + "': " + ec.message());
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MemBufOrErr =
+      MemoryBuffer::getFileOrSTDIN(InputFilename);
+  if (std::error_code EC = MemBufOrErr.getError())
+    return Error("Error reading '" + InputFilename + "': " + EC.message());
+  std::unique_ptr<MemoryBuffer> MemBuf = std::move(MemBufOrErr.get());
 
   if (MemBuf->getBufferSize() & 3)
     return Error("Bitcode stream should be a multiple of 4 bytes in length");
diff --git a/llvm/tools/llvm-cov/llvm-cov.cpp b/llvm/tools/llvm-cov/llvm-cov.cpp
index 04de443..18cc1b1 100644
--- a/llvm/tools/llvm-cov/llvm-cov.cpp
+++ b/llvm/tools/llvm-cov/llvm-cov.cpp
@@ -97,27 +97,29 @@ void reportCoverage(StringRef SourceFile) {
                          : InputGCDA;
   GCOVFile GF;
 
-  std::unique_ptr<MemoryBuffer> GCNO_Buff;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(GCNO, GCNO_Buff)) {
-    errs() << GCNO << ": " << ec.message() << "\n";
+  ErrorOr<std::unique_ptr<MemoryBuffer>> GCNO_Buff =
+      MemoryBuffer::getFileOrSTDIN(GCNO);
+  if (std::error_code EC = GCNO_Buff.getError()) {
+    errs() << GCNO << ": " << EC.message() << "\n";
     return;
   }
-  GCOVBuffer GCNO_GB(GCNO_Buff.get());
+  GCOVBuffer GCNO_GB(GCNO_Buff.get().get());
   if (!GF.readGCNO(GCNO_GB)) {
     errs() << "Invalid .gcno File!\n";
     return;
   }
 
-  std::unique_ptr<MemoryBuffer> GCDA_Buff;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(GCDA, GCDA_Buff)) {
-    if (ec != errc::no_such_file_or_directory) {
-      errs() << GCDA << ": " << ec.message() << "\n";
+  ErrorOr<std::unique_ptr<MemoryBuffer>> GCDA_Buff =
+      MemoryBuffer::getFileOrSTDIN(GCDA);
+  if (std::error_code EC = GCDA_Buff.getError()) {
+    if (EC != errc::no_such_file_or_directory) {
+      errs() << GCDA << ": " << EC.message() << "\n";
       return;
     }
     // Clear the filename to make it clear we didn't read anything.
     GCDA = "-";
   } else {
-    GCOVBuffer GCDA_GB(GCDA_Buff.get());
+    GCOVBuffer GCDA_GB(GCDA_Buff.get().get());
     if (!GF.readGCDA(GCDA_GB)) {
       errs() << "Invalid .gcda File!\n";
       return;
diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index 0eb6e4f..f44b0e3 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -66,14 +66,15 @@ DumpType("debug-dump", cl::init(DIDT_All),
         clEnumValEnd));
 
 static void DumpInput(const StringRef &Filename) {
-  std::unique_ptr<MemoryBuffer> Buff;
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buff =
+      MemoryBuffer::getFileOrSTDIN(Filename);
 
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, Buff)) {
-    errs() << Filename << ": " << ec.message() << "\n";
+  if (std::error_code EC = Buff.getError()) {
+    errs() << Filename << ": " << EC.message() << "\n";
     return;
   }
 
-  ErrorOr<ObjectFile *> ObjOrErr(ObjectFile::createObjectFile(Buff));
+  ErrorOr<ObjectFile *> ObjOrErr(ObjectFile::createObjectFile(Buff.get()));
   if (std::error_code EC = ObjOrErr.getError()) {
     errs() << Filename << ": " << EC.message() << '\n';
     return;
diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp
index 72294ca..4c5b230 100644
--- a/llvm/tools/llvm-mc/llvm-mc.cpp
+++ b/llvm/tools/llvm-mc/llvm-mc.cpp
@@ -367,13 +367,13 @@ int main(int argc, char **argv) {
   if (!TheTarget)
     return 1;
 
-  std::unique_ptr<MemoryBuffer> BufferPtr;
-  if (std::error_code ec =
-          MemoryBuffer::getFileOrSTDIN(InputFilename, BufferPtr)) {
-    errs() << ProgName << ": " << ec.message() << '\n';
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
+      MemoryBuffer::getFileOrSTDIN(InputFilename);
+  if (std::error_code EC = BufferPtr.getError()) {
+    errs() << ProgName << ": " << EC.message() << '\n';
     return 1;
   }
-  MemoryBuffer *Buffer = BufferPtr.release();
+  MemoryBuffer *Buffer = BufferPtr->release();
 
   SourceMgr SrcMgr;
 
diff --git a/llvm/tools/llvm-mcmarkup/llvm-mcmarkup.cpp b/llvm/tools/llvm-mcmarkup/llvm-mcmarkup.cpp
index cbb0d51..a878f11 100644
--- a/llvm/tools/llvm-mcmarkup/llvm-mcmarkup.cpp
+++ b/llvm/tools/llvm-mcmarkup/llvm-mcmarkup.cpp
@@ -135,12 +135,13 @@ MarkupTag MarkupParser::parseTag() {
 }
 
 static void parseMCMarkup(StringRef Filename) {
-  std::unique_ptr<MemoryBuffer> BufferPtr;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, BufferPtr)) {
-    errs() << ToolName << ": " << ec.message() << '\n';
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (std::error_code EC = BufferPtr.getError()) {
+    errs() << ToolName << ": " << EC.message() << '\n';
     return;
   }
-  MemoryBuffer *Buffer = BufferPtr.release();
+  MemoryBuffer *Buffer = BufferPtr->release();
 
   SourceMgr SrcMgr;
 
diff --git a/llvm/tools/llvm-nm/llvm-nm.cpp b/llvm/tools/llvm-nm/llvm-nm.cpp
index d391854..8a89dd8 100644
--- a/llvm/tools/llvm-nm/llvm-nm.cpp
+++ b/llvm/tools/llvm-nm/llvm-nm.cpp
@@ -805,9 +805,11 @@ static bool checkMachOAndArchFlags(SymbolicFile *O, std::string &Filename) {
 }
 
 static void dumpSymbolNamesFromFile(std::string &Filename) {
-  std::unique_ptr<MemoryBuffer> Buffer;
-  if (error(MemoryBuffer::getFileOrSTDIN(Filename, Buffer), Filename))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (error(BufferOrErr.getError(), Filename))
     return;
+  std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrErr.get());
 
   LLVMContext &Context = getGlobalContext();
   ErrorOr<Binary *> BinaryOrErr = createBinary(Buffer, &Context);
diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index 74fdfef..4b46ac4 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -195,15 +195,15 @@ static void DisassembleInputMachO2(StringRef Filename,
                                    MachOObjectFile *MachOOF);
 
 void llvm::DisassembleInputMachO(StringRef Filename) {
-  std::unique_ptr<MemoryBuffer> Buff;
-
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, Buff)) {
-    errs() << "llvm-objdump: " << Filename << ": " << ec.message() << "\n";
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buff =
+      MemoryBuffer::getFileOrSTDIN(Filename);
+  if (std::error_code EC = Buff.getError()) {
+    errs() << "llvm-objdump: " << Filename << ": " << EC.message() << "\n";
     return;
   }
 
   std::unique_ptr<MachOObjectFile> MachOOF(static_cast<MachOObjectFile *>(
-      ObjectFile::createMachOObjectFile(Buff).get()));
+      ObjectFile::createMachOObjectFile(Buff.get()).get()));
 
   DisassembleInputMachO2(Filename, MachOOF.get());
 }
@@ -288,12 +288,13 @@ static void DisassembleInputMachO2(StringRef Filename,
     // A separate DSym file path was specified, parse it as a macho file,
     // get the sections and supply it to the section name parsing machinery.
     if (!DSYMFile.empty()) {
-      std::unique_ptr<MemoryBuffer> Buf;
-      if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(DSYMFile, Buf)) {
-        errs() << "llvm-objdump: " << Filename << ": " << ec.message() << '\n';
+      ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
+          MemoryBuffer::getFileOrSTDIN(DSYMFile);
+      if (std::error_code EC = Buf.getError()) {
+        errs() << "llvm-objdump: " << Filename << ": " << EC.message() << '\n';
         return;
       }
-      DbgObj = ObjectFile::createMachOObjectFile(Buf).get();
+      DbgObj = ObjectFile::createMachOObjectFile(Buf.get()).get();
     }
 
     // Setup the DIContext
diff --git a/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp b/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
index fcda9e7f..45734f4 100644
--- a/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
+++ b/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
@@ -175,14 +175,16 @@ static int printLineInfoForInput() {
     RuntimeDyld Dyld(&MemMgr);
 
     // Load the input memory buffer.
-    std::unique_ptr<MemoryBuffer> InputBuffer;
-    std::unique_ptr<ObjectImage> LoadedObject;
-    if (std::error_code ec =
-            MemoryBuffer::getFileOrSTDIN(InputFileList[i], InputBuffer))
-      return Error("unable to read input: '" + ec.message() + "'");
 
+    ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
+        MemoryBuffer::getFileOrSTDIN(InputFileList[i]);
+    if (std::error_code EC = InputBuffer.getError())
+      return Error("unable to read input: '" + EC.message() + "'");
+
+    std::unique_ptr<ObjectImage> LoadedObject;
     // Load the object file
-    LoadedObject.reset(Dyld.loadObject(new ObjectBuffer(InputBuffer.release())));
+    LoadedObject.reset(
+        Dyld.loadObject(new ObjectBuffer(InputBuffer.get().release())));
     if (!LoadedObject) {
       return Error(Dyld.getErrorString());
     }
@@ -236,14 +238,14 @@ static int executeInput() {
     InputFileList.push_back("-");
   for(unsigned i = 0, e = InputFileList.size(); i != e; ++i) {
     // Load the input memory buffer.
-    std::unique_ptr<MemoryBuffer> InputBuffer;
+    ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
+        MemoryBuffer::getFileOrSTDIN(InputFileList[i]);
+    if (std::error_code EC = InputBuffer.getError())
+      return Error("unable to read input: '" + EC.message() + "'");
     std::unique_ptr<ObjectImage> LoadedObject;
-    if (std::error_code ec =
-            MemoryBuffer::getFileOrSTDIN(InputFileList[i], InputBuffer))
-      return Error("unable to read input: '" + ec.message() + "'");
-
     // Load the object file
-    LoadedObject.reset(Dyld.loadObject(new ObjectBuffer(InputBuffer.release())));
+    LoadedObject.reset(
+        Dyld.loadObject(new ObjectBuffer(InputBuffer.get().release())));
     if (!LoadedObject) {
       return Error(Dyld.getErrorString());
     }
@@ -285,13 +287,14 @@ static int executeInput() {
 
 static int checkAllExpressions(RuntimeDyldChecker &Checker) {
   for (const auto& CheckerFileName : CheckFiles) {
-    std::unique_ptr<MemoryBuffer> CheckerFileBuf;
-    if (std::error_code EC =
-          MemoryBuffer::getFileOrSTDIN(CheckerFileName, CheckerFileBuf))
+    ErrorOr<std::unique_ptr<MemoryBuffer>> CheckerFileBuf =
+        MemoryBuffer::getFileOrSTDIN(CheckerFileName);
+    if (std::error_code EC = CheckerFileBuf.getError())
       return Error("unable to read input '" + CheckerFileName + "': " +
                    EC.message());
 
-    if (!Checker.checkAllRulesInBuffer("# rtdyld-check:", CheckerFileBuf.get()))
+    if (!Checker.checkAllRulesInBuffer("# rtdyld-check:",
+                                       CheckerFileBuf.get().get()))
       return Error("some checks in '" + CheckerFileName + "' failed");
   }
   return 0;
@@ -350,15 +353,15 @@ static int linkAndVerify() {
     InputFileList.push_back("-");
   for(unsigned i = 0, e = InputFileList.size(); i != e; ++i) {
     // Load the input memory buffer.
-    std::unique_ptr<MemoryBuffer> InputBuffer;
-    std::unique_ptr<ObjectImage> LoadedObject;
-    if (std::error_code ec =
-            MemoryBuffer::getFileOrSTDIN(InputFileList[i], InputBuffer))
-      return Error("unable to read input: '" + ec.message() + "'");
+    ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
+        MemoryBuffer::getFileOrSTDIN(InputFileList[i]);
+    if (std::error_code EC = InputBuffer.getError())
+      return Error("unable to read input: '" + EC.message() + "'");
 
+    std::unique_ptr<ObjectImage> LoadedObject;
     // Load the object file
     LoadedObject.reset(
-      Dyld.loadObject(new ObjectBuffer(InputBuffer.release())));
+        Dyld.loadObject(new ObjectBuffer(InputBuffer.get().release())));
     if (!LoadedObject) {
       return Error(Dyld.getErrorString());
     }
diff --git a/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp b/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
index ebbae39..c1d39ef 100644
--- a/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
+++ b/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
@@ -220,10 +220,11 @@ static std::string getDarwinDWARFResourceForPath(const std::string &Path) {
 }
 
 static bool checkFileCRC(StringRef Path, uint32_t CRCHash) {
-  std::unique_ptr<MemoryBuffer> MB;
-  if (MemoryBuffer::getFileOrSTDIN(Path, MB))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
+      MemoryBuffer::getFileOrSTDIN(Path);
+  if (!MB)
     return false;
-  return !zlib::isAvailable() || CRCHash == zlib::crc32(MB->getBuffer());
+  return !zlib::isAvailable() || CRCHash == zlib::crc32(MB.get()->getBuffer());
 }
 
 static bool findDebugBinary(const std::string &OrigPath,
diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
index b3f5938..b401f9a 100644
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -88,10 +88,10 @@ bool lto_module_is_object_file(const char* path) {
 
 bool lto_module_is_object_file_for_target(const char* path,
                                           const char* target_triplet_prefix) {
-  std::unique_ptr<MemoryBuffer> buffer;
-  if (MemoryBuffer::getFile(path, buffer))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer = MemoryBuffer::getFile(path);
+  if (!Buffer)
     return false;
-  return LTOModule::isBitcodeForTarget(buffer.get(), target_triplet_prefix);
+  return LTOModule::isBitcodeForTarget(Buffer->get(), target_triplet_prefix);
 }
 
 bool lto_module_is_object_file_in_memory(const void* mem, size_t length) {
diff --git a/llvm/tools/yaml2obj/yaml2obj.cpp b/llvm/tools/yaml2obj/yaml2obj.cpp
index dd41951..945fad1 100644
--- a/llvm/tools/yaml2obj/yaml2obj.cpp
+++ b/llvm/tools/yaml2obj/yaml2obj.cpp
@@ -91,8 +91,9 @@ int main(int argc, char **argv) {
     return 1;
   }
 
-  std::unique_ptr<MemoryBuffer> Buf;
-  if (MemoryBuffer::getFileOrSTDIN(Input, Buf))
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
+      MemoryBuffer::getFileOrSTDIN(Input);
+  if (!Buf)
     return 1;
 
   ConvertFuncPtr Convert = nullptr;
@@ -105,7 +106,7 @@ int main(int argc, char **argv) {
     return 1;
   }
 
-  yaml::Input YIn(Buf->getBuffer());
+  yaml::Input YIn(Buf.get()->getBuffer());
 
   int Res = convertYAML(YIn, Out->os(), Convert);
   if (Res == 0)
diff --git a/llvm/unittests/Support/MemoryBufferTest.cpp b/llvm/unittests/Support/MemoryBufferTest.cpp
index 98af5c4..93bf301 100644
--- a/llvm/unittests/Support/MemoryBufferTest.cpp
+++ b/llvm/unittests/Support/MemoryBufferTest.cpp
@@ -77,11 +77,11 @@ TEST_F(MemoryBufferTest, NullTerminator4K) {
   }
   OF.close();
 
-  OwningBuffer MB;
-  std::error_code EC = MemoryBuffer::getFile(TestPath.c_str(), MB);
+  ErrorOr<OwningBuffer> MB = MemoryBuffer::getFile(TestPath.c_str());
+  std::error_code EC = MB.getError();
   ASSERT_FALSE(EC);
 
-  const char *BufData = MB->getBufferStart();
+  const char *BufData = MB.get()->getBufferStart();
   EXPECT_EQ('f', BufData[4095]);
   EXPECT_EQ('\0', BufData[4096]);
 }
@@ -146,15 +146,16 @@ void MemoryBufferTest::testGetOpenFileSlice(bool Reopen) {
     EXPECT_FALSE(sys::fs::openFileForRead(TestPath.c_str(), TestFD));
   }
 
-  OwningBuffer Buf;
-  std::error_code EC =
-      MemoryBuffer::getOpenFileSlice(TestFD, TestPath.c_str(), Buf,
+  ErrorOr<OwningBuffer> Buf =
+      MemoryBuffer::getOpenFileSlice(TestFD, TestPath.c_str(),
                                      40000, // Size
                                      80000  // Offset
                                      );
+
+  std::error_code EC = Buf.getError();
   EXPECT_FALSE(EC);
 
-  StringRef BufData = Buf->getBuffer();
+  StringRef BufData = Buf.get()->getBuffer();
   EXPECT_EQ(BufData.size(), 40000U);
   EXPECT_EQ(BufData[0], '0');
   EXPECT_EQ(BufData[9], '9');
diff --git a/llvm/utils/FileCheck/FileCheck.cpp b/llvm/utils/FileCheck/FileCheck.cpp
index 978e05f..d88cf36 100644
--- a/llvm/utils/FileCheck/FileCheck.cpp
+++ b/llvm/utils/FileCheck/FileCheck.cpp
@@ -820,17 +820,18 @@ static StringRef FindFirstMatchingPrefix(StringRef &Buffer,
 /// Returns true in case of an error, false otherwise.
 static bool ReadCheckFile(SourceMgr &SM,
                           std::vector<CheckString> &CheckStrings) {
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(CheckFilename, File)) {
-    errs() << "Could not open check file '" << CheckFilename << "': "
-           << ec.message() << '\n';
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(CheckFilename);
+  if (std::error_code EC = FileOrErr.getError()) {
+    errs() << "Could not open check file '" << CheckFilename
+           << "': " << EC.message() << '\n';
     return true;
   }
 
   // If we want to canonicalize whitespace, strip excess whitespace from the
   // buffer containing the CHECK lines. Remove DOS style line endings.
-  MemoryBuffer *F =
-    CanonicalizeInputFile(File.release(), NoCanonicalizeWhiteSpace);
+  MemoryBuffer *F = CanonicalizeInputFile(FileOrErr.get().release(),
+                                          NoCanonicalizeWhiteSpace);
 
   SM.AddNewSourceBuffer(F, SMLoc());
 
@@ -1223,12 +1224,14 @@ int main(int argc, char **argv) {
     return 2;
 
   // Open the file to check and add it to SourceMgr.
-  std::unique_ptr<MemoryBuffer> File;
-  if (std::error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename, File)) {
-    errs() << "Could not open input file '" << InputFilename << "': "
-           << ec.message() << '\n';
+  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
+      MemoryBuffer::getFileOrSTDIN(InputFilename);
+  if (std::error_code EC = FileOrErr.getError()) {
+    errs() << "Could not open input file '" << InputFilename
+           << "': " << EC.message() << '\n';
     return 2;
   }
+  std::unique_ptr<MemoryBuffer> File = std::move(FileOrErr.get());
 
   if (File->getBufferSize() == 0) {
     errs() << "FileCheck error: '" << InputFilename << "' is empty.\n";
diff --git a/llvm/utils/yaml-bench/YAMLBench.cpp b/llvm/utils/yaml-bench/YAMLBench.cpp
index 39b8f72..e88ce5d 100644
--- a/llvm/utils/yaml-bench/YAMLBench.cpp
+++ b/llvm/utils/yaml-bench/YAMLBench.cpp
@@ -188,9 +188,11 @@ static std::string createJSONText(size_t MemoryMB, unsigned ValueSize) {
 int main(int argc, char **argv) {
   llvm::cl::ParseCommandLineOptions(argc, argv);
   if (Input.getNumOccurrences()) {
-    std::unique_ptr<MemoryBuffer> Buf;
-    if (MemoryBuffer::getFileOrSTDIN(Input, Buf))
+    ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
+        MemoryBuffer::getFileOrSTDIN(Input);
+    if (!BufOrErr)
       return 1;
+    std::unique_ptr<MemoryBuffer> Buf = std::move(BufOrErr.get());
 
     llvm::SourceMgr sm;
     if (DumpTokens) {