diff --git a/llvm/unittests/Support/FileOutputBufferTest.cpp b/llvm/unittests/Support/FileOutputBufferTest.cpp
new file mode 100644
index 0000000..edd350a
--- /dev/null
+++ b/llvm/unittests/Support/FileOutputBufferTest.cpp
@@ -0,0 +1,137 @@
+//===- llvm/unittest/Support/FileOutputBuffer.cpp - unit tests ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/PathV2.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::sys;
+
+#define ASSERT_NO_ERROR(x) \
+  if (error_code ASSERT_NO_ERROR_ec = x) { \
+    errs() << #x ": did not return errc::success.\n" \
+            << "error number: " << ASSERT_NO_ERROR_ec.value() << "\n" \
+            << "error message: " << ASSERT_NO_ERROR_ec.message() << "\n"; \
+  } else {}
+
+namespace {
+
+
+// NOTE: Temporarily run this test on unix only.  Once the file mapping
+// routines are ported to Windows, this conditional can be removed.
+#if LLVM_ON_UNIX
+
+
+TEST(FileOutputBuffer, Test) {
+  // Create unique temporary directory for these tests
+  SmallString<128> TestDirectory;
+  {
+    int fd;
+    ASSERT_NO_ERROR(
+      fs::unique_file("FileOutputBuffer-test-%%-%%-%%-%%/dir", fd,
+                      TestDirectory));
+    ::close(fd);
+    TestDirectory = path::parent_path(TestDirectory);
+  }
+     
+  // TEST 1: Verify commit case.
+  SmallString<128> File1(TestDirectory);
+	File1.append("/file1");
+  {
+    OwningPtr<FileOutputBuffer> Buffer;
+    ASSERT_NO_ERROR(FileOutputBuffer::create(File1, 8192, Buffer));
+    // Start buffer with special header.
+    memcpy(Buffer->getBufferStart(), "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Write to end of buffer to verify it is writable.
+    memcpy(Buffer->getBufferEnd() - 20, "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Commit buffer.
+    ASSERT_NO_ERROR(Buffer->commit());
+  }
+  // Verify file exists and starts with special header.
+  bool MagicMatches = false;
+  ASSERT_NO_ERROR(fs::has_magic(Twine(File1), Twine("AABBCCDDEEFFGGHHIIJJ"), 
+                                                                MagicMatches));
+  EXPECT_TRUE(MagicMatches);
+  // Verify file is correct size.
+  uint64_t File1Size;
+  ASSERT_NO_ERROR(fs::file_size(Twine(File1), File1Size));
+  ASSERT_EQ(File1Size, 8192ULL);
+
+ 	// TEST 2: Verify abort case.
+  SmallString<128> File2(TestDirectory);
+	File2.append("/file2");
+  {
+    OwningPtr<FileOutputBuffer> Buffer2;
+    ASSERT_NO_ERROR(FileOutputBuffer::create(File2, 8192, Buffer2));
+    // Fill buffer with special header.
+    memcpy(Buffer2->getBufferStart(), "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Do *not* commit buffer.
+  }
+  // Verify file does not exist (because buffer not commited).
+  bool Exists = false;
+  ASSERT_NO_ERROR(fs::exists(Twine(File2), Exists));
+  EXPECT_FALSE(Exists);  
+
+
+  // TEST 3: Verify sizing down case.
+  SmallString<128> File3(TestDirectory);
+	File3.append("/file3");
+  {
+    OwningPtr<FileOutputBuffer> Buffer;
+    ASSERT_NO_ERROR(FileOutputBuffer::create(File3, 8192000, Buffer));
+    // Start buffer with special header.
+    memcpy(Buffer->getBufferStart(), "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Write to end of buffer to verify it is writable.
+    memcpy(Buffer->getBufferEnd() - 20, "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Commit buffer, but size down to smaller size
+    ASSERT_NO_ERROR(Buffer->commit(5000));
+  }
+  // Verify file exists and starts with special header.
+  bool MagicMatches3 = false;
+  ASSERT_NO_ERROR(fs::has_magic(Twine(File3), Twine("AABBCCDDEEFFGGHHIIJJ"), 
+                                                              MagicMatches3));
+  EXPECT_TRUE(MagicMatches3);
+  // Verify file is correct size.
+  uint64_t File3Size;
+  ASSERT_NO_ERROR(fs::file_size(Twine(File3), File3Size));
+  ASSERT_EQ(File3Size, 5000ULL);
+
+
+  // TEST 4: Verify file can be made executable.
+  SmallString<128> File4(TestDirectory);
+	File4.append("/file4");
+  {
+    OwningPtr<FileOutputBuffer> Buffer;
+    ASSERT_NO_ERROR(FileOutputBuffer::create(File4, 8192, Buffer, 
+                                              FileOutputBuffer::F_executable));
+    // Start buffer with special header.
+    memcpy(Buffer->getBufferStart(), "AABBCCDDEEFFGGHHIIJJ", 20);
+    // Commit buffer.
+    ASSERT_NO_ERROR(Buffer->commit());
+  }
+  // Verify file exists and is executable.
+  fs::file_status Status;
+  ASSERT_NO_ERROR(fs::status(Twine(File4), Status));
+  bool IsExecutable = (Status.permissions() & fs::owner_exe);
+  EXPECT_TRUE(IsExecutable);
+
+  // Clean up.
+  uint32_t RemovedCount;
+  ASSERT_NO_ERROR(fs::remove_all(TestDirectory.str(), RemovedCount));
+}
+
+#endif // LLVM_ON_UNIX
+
+} // anonymous namespace