Index: include/llvm/Support/FileSystem.h
===================================================================
--- include/llvm/Support/FileSystem.h
+++ include/llvm/Support/FileSystem.h
@@ -32,6 +32,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/TimeValue.h"
 #include <ctime>
 #include <iterator>
@@ -648,6 +649,18 @@
 
 std::error_code getUniqueID(const Twine Path, UniqueID &Result);
 
+/// @brief Get disk space usage information.
+///
+/// Note: Users must be careful about "Time Of Check, Time Of Use" kind of bug.
+/// Note: Windows reports results according to the quota allocated to the user.
+///
+/// @param Path Input path.
+/// @param SpaceInfo Set to the capacity, free, and available space on the
+///        device \a Path is on.
+/// @results errc::success if result has been successfully set, otherwise a
+///          platform specific error_code.
+ErrorOr<space_info> disk_space(const Twine Path);
+
 /// This class represents a memory mapped file. It is based on
 /// boost::iostreams::mapped_file.
 class mapped_file_region {
Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc
+++ lib/Support/Unix/Path.inc
@@ -60,6 +60,24 @@
 # define PATH_MAX 4096
 #endif
 
+#include <sys/types.h>
+#if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(__ANDROID__)
+#include <sys/statvfs.h>
+#define STATVFS statvfs
+#define STATVFS_F_FRSIZE(vfs) vfs.f_frsize
+#else
+#ifdef __OpenBSD__
+#include <sys/param.h>
+#elif defined(__ANDROID__)
+#include <sys/vfs.h>
+#else
+#include <sys/mount.h>
+#endif
+#define STATVFS statfs
+#define STATVFS_F_FRSIZE(vfs) static_cast<uint64_t>(vfs.f_bsize)
+#endif
+
+
 using namespace llvm;
 
 namespace llvm {
@@ -70,7 +88,7 @@
     defined(__linux__) || defined(__CYGWIN__) || defined(__DragonFly__)
 static int
 test_dir(char ret[PATH_MAX], const char *dir, const char *bin)
-{  
+{
   struct stat sb;
   char fullpath[PATH_MAX];
 
@@ -190,6 +208,18 @@
   return UniqueID(fs_st_dev, fs_st_ino);
 }
 
+ErrorOr<space_info> disk_space(const Twine Path) {
+  struct STATVFS Vfs;
+  if (::STATVFS(Path.str().c_str(), &Vfs))
+    return std::error_code(errno, std::generic_category());
+  auto FrSize = STATVFS_F_FRSIZE(Vfs);
+  space_info SpaceInfo;
+  SpaceInfo.capacity = static_cast<uint64_t>(Vfs.f_blocks) * FrSize;
+  SpaceInfo.free = static_cast<uint64_t>(Vfs.f_bfree) * FrSize;
+  SpaceInfo.available = static_cast<uint64_t>(Vfs.f_bavail) * FrSize;
+  return SpaceInfo;
+}
+
 std::error_code current_path(SmallVectorImpl<char> &result) {
   result.clear();
 
Index: lib/Support/Windows/Path.inc
===================================================================
--- lib/Support/Windows/Path.inc
+++ lib/Support/Windows/Path.inc
@@ -151,6 +151,19 @@
   return UniqueID(VolumeSerialNumber, FileID);
 }
 
+ErrorOr<space_info> disk_space(const Twine Path) {
+  PULARGE_INTEGER Avail, Total, Free;
+  if (!::GetDiskFreeSpaceExW(Path.str().c_str(), &Avail, &Total, &Free))
+    return mapWindowsError(::GetLastError());
+  space_info SpaceInfo;
+  SpaceInfo.capacity =
+      (static_cast<uint64_t>(Total.HighPart) << 32) + Total.LowPart;
+  SpaceInfo.Free = (static_cast<uint64_t>(Free.HighPart) << 32) + Free.LowPart;
+  SpaceInfo.available =
+      (static_cast<uint64_t>(Avail.HighPart) << 32) + Avail.LowPart;
+  return SpaceInfo;
+}
+
 TimeValue file_status::getLastAccessedTime() const {
   ULARGE_INTEGER UI;
   UI.LowPart = LastAccessedTimeLow;