Index: include/llvm/Support/FileSystem.h
===================================================================
--- include/llvm/Support/FileSystem.h
+++ include/llvm/Support/FileSystem.h
@@ -665,15 +665,16 @@
 ///
 /// @param Path File to set permissions on.
 /// @param Permissions New file permissions.
-/// @param RespectUmask If true then Permissions will be changed to respect the
-///        umask of the current process.
 /// @returns errc::success if the permissions were successfully set, otherwise
 ///          a platform-specific error_code.
 /// @note On Windows, all permissions except *_write are ignored. Using any of
 ///       owner_write, group_write, or all_write will make the file writable.
 ///       Otherwise, the file will be marked as read-only.
-std::error_code setPermissions(const Twine &Path, perms Permissions,
-                               bool RespectUmask = false);
+std::error_code setPermissions(const Twine &Path, perms Permissions);
+
+// TODO Delete the path based overload once we implement the FD based overload
+// on Windows.
+std::error_code setPermissions(int FD, perms Permissions);
 
 /// Get file permissions.
 ///
Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc
+++ lib/Support/Unix/Path.inc
@@ -702,19 +702,21 @@
   return Mask;
 }
 
-std::error_code setPermissions(const Twine &Path, perms Permissions,
-                               bool RespectUmask) {
+std::error_code setPermissions(const Twine &Path, perms Permissions) {
   SmallString<128> PathStorage;
   StringRef P = Path.toNullTerminatedStringRef(PathStorage);
 
-  if (RespectUmask)
-    Permissions = static_cast<perms>(Permissions & ~getUmask());
-
   if (::chmod(P.begin(), Permissions))
     return std::error_code(errno, std::generic_category());
   return std::error_code();
 }
 
+std::error_code setPermissions(int FD, perms Permissions) {
+  if (::fchmod(FD, Permissions))
+    return std::error_code(errno, std::generic_category());
+  return std::error_code();
+}
+
 std::error_code setLastAccessAndModificationTime(int FD, TimePoint<> AccessTime,
                                                  TimePoint<> ModificationTime) {
 #if defined(HAVE_FUTIMENS)
Index: lib/Support/Windows/Path.inc
===================================================================
--- lib/Support/Windows/Path.inc
+++ lib/Support/Windows/Path.inc
@@ -742,8 +742,7 @@
   return 0;
 }
 
-std::error_code setPermissions(const Twine &Path, perms Permissions,
-                               bool /*RespectUmask*/) {
+std::error_code setPermissions(const Twine &Path, perms Permissions) {
   SmallVector<wchar_t, 128> PathUTF16;
   if (std::error_code EC = widenPath(Path, PathUTF16))
     return EC;
@@ -774,6 +773,11 @@
   return std::error_code();
 }
 
+std::error_code setPermissions(int FD, perms Permissions) {
+  // FIXME Not implemented.
+  return std::make_error_code(std::errc::not_supported);
+}
+
 std::error_code setLastAccessAndModificationTime(int FD, TimePoint<> AccessTime,
                                                  TimePoint<> ModificationTime) {
   FILETIME AccessFT = toFILETIME(AccessTime);
Index: test/tools/llvm-objcopy/ELF/mirror-permissions-unix.test
===================================================================
--- test/tools/llvm-objcopy/ELF/mirror-permissions-unix.test
+++ test/tools/llvm-objcopy/ELF/mirror-permissions-unix.test
@@ -36,6 +36,12 @@
 # RUN: ls -l %t1 | cut -f 1 -d ' ' > %t1.perms
 # RUN: cmp %t1.perms %t.0640
 
+## Don't set the permission of a character special file, otherwise there will
+## be an EPERM error (or worse: root may change the permission).
+# RUN: ls -l /dev/null | cut -f 1 -d ' ' > %tnull.perms
+# RUN: llvm-objcopy %t /dev/null
+# RUN: ls -l /dev/null | cut -f 1 -d ' ' | diff - %tnull.perms
+
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
Index: tools/llvm-objcopy/llvm-objcopy.cpp
===================================================================
--- tools/llvm-objcopy/llvm-objcopy.cpp
+++ tools/llvm-objcopy/llvm-objcopy.cpp
@@ -222,9 +222,20 @@
             FD, Stat.getLastAccessedTime(), Stat.getLastModificationTime()))
       return createFileError(Filename, EC);
 
-  if (auto EC = sys::fs::setPermissions(Filename, Stat.permissions(),
-                                        /*respectUmask=*/true))
+  sys::fs::file_status OStat;
+  if (std::error_code EC = sys::fs::status(FD, OStat))
     return createFileError(Filename, EC);
+  if (OStat.type() == sys::fs::file_type::regular_file)
+#ifdef _WIN32
+    if (auto EC = sys::fs::setPermissions(
+            Filename, static_cast<sys::fs::perms>(Stat.permissions() &
+                                                  ~sys::fs::getUmask())))
+#else
+    if (auto EC = sys::fs::setPermissions(
+            FD, static_cast<sys::fs::perms>(Stat.permissions() &
+                                            ~sys::fs::getUmask())))
+#endif
+      return createFileError(Filename, EC);
 
   if (auto EC = sys::Process::SafelyCloseFileDescriptor(FD))
     return createFileError(Filename, EC);
Index: unittests/Support/Path.cpp
===================================================================
--- unittests/Support/Path.cpp
+++ unittests/Support/Path.cpp
@@ -1550,19 +1550,20 @@
 
   fs::perms AllRWE = static_cast<fs::perms>(0777);
 
-  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE /*RespectUmask=false*/));
+  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE));
 
   ErrorOr<fs::perms> Perms = fs::getPermissions(TempPath);
   ASSERT_TRUE(!!Perms);
   EXPECT_EQ(Perms.get(), AllRWE) << "Should have ignored umask by default";
 
-  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE, /*RespectUmask=*/false));
+  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE));
 
   Perms = fs::getPermissions(TempPath);
   ASSERT_TRUE(!!Perms);
   EXPECT_EQ(Perms.get(), AllRWE) << "Should have ignored umask";
 
-  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE, /*RespectUmask=*/true));
+  ASSERT_NO_ERROR(
+      fs::setPermissions(FD, static_cast<fs::perms>(AllRWE & ~fs::getUmask())));
   Perms = fs::getPermissions(TempPath);
   ASSERT_TRUE(!!Perms);
   EXPECT_EQ(Perms.get(), static_cast<fs::perms>(0755))
@@ -1570,7 +1571,8 @@
 
   (void)::umask(0057);
 
-  ASSERT_NO_ERROR(fs::setPermissions(TempPath, AllRWE, /*RespectUmask=*/true));
+  ASSERT_NO_ERROR(
+      fs::setPermissions(FD, static_cast<fs::perms>(AllRWE & ~fs::getUmask())));
   Perms = fs::getPermissions(TempPath);
   ASSERT_TRUE(!!Perms);
   EXPECT_EQ(Perms.get(), static_cast<fs::perms>(0720))