--- a/tools/mach_commands.py
+++ b/tools/mach_commands.py
@@ -226,22 +226,21 @@ class FormatProvider(MachCommandBase):
     @Command('clang-format', category='misc',
         description='Run clang-format on current changes')
     @CommandArgument('--show', '-s', action = 'store_true',
         help = 'Show diff output on instead of applying changes')
     def clang_format(self, show=False):
         import urllib2
 
         plat = platform.system()
-        fmt = plat.lower() + "/clang-format-3.5"
-        fmt_diff = "clang-format-diff-3.5"
+        fmt = plat.lower() + "/clang-format-4.0"
+        fmt_diff = "clang-format-diff-4.0"
 
-        # We are currently using a modified version of clang-format hosted on people.mozilla.org.
-        # This is a temporary work around until we upstream the necessary changes and we can use
-        # a system version of clang-format. See bug 961541.
+        # We are currently using an unmodified snapshot of upstream clang-format.
+        # This is a temporary work around until clang 4.0 has been released with our changes.
         if plat == "Windows":
             fmt += ".exe"
         else:
             arch = os.uname()[4]
             if (plat != "Linux" and plat != "Darwin") or arch != 'x86_64':
                 print("Unsupported platform " + plat + "/" + arch +
                       ". Supported platforms are Windows/*, Linux/x86_64 and Darwin/x86_64")
                 return 1
@@ -262,17 +261,17 @@ class FormatProvider(MachCommandBase):
 
         from subprocess import Popen, PIPE
 
         if os.path.exists(".hg"):
             diff_process = Popen(["hg", "diff", "-U0", "-r", "tip^",
                                   "--include", "glob:**.c", "--include", "glob:**.cpp", "--include", "glob:**.h",
                                   "--exclude", "listfile:.clang-format-ignore"], stdout=PIPE)
         else:
-            git_process = Popen(["git", "diff", "-U0", "HEAD^"], stdout=PIPE)
+            git_process = Popen(["git", "diff", "--no-color", "-U0", "HEAD^"], stdout=PIPE)
             try:
                 diff_process = Popen(["filterdiff", "--include=*.h", "--include=*.cpp",
                                       "--exclude-from-file=.clang-format-ignore"],
                                      stdin=git_process.stdout, stdout=PIPE)
             except OSError as e:
                 if e.errno == errno.ENOENT:
                     print("Can't find filterdiff. Please install patchutils.")
                 else:
@@ -282,19 +281,20 @@ class FormatProvider(MachCommandBase):
 
         args = [sys.executable, clang_format_diff, "-p1"]
         if not show:
            args.append("-i")
         cf_process = Popen(args, stdin=diff_process.stdout)
         return cf_process.communicate()[0]
 
     def locate_or_fetch(self, root):
+        import urllib2
         target = os.path.join(self._mach_context.state_dir, os.path.basename(root))
         if not os.path.exists(target):
-            site = "https://people.mozilla.org/~ajones/clang-format/"
+            site = "https://people.mozilla.org/~sledru/clang-format/"
             if self.prompt and raw_input("Download clang-format executables from {0} (yN)? ".format(site)).lower() != 'y':
                 print("Download aborted.")
                 return 1
             self.prompt = False
 
             u = site + root
             print("Downloading {0} to {1}".format(u, target))
             data = urllib2.urlopen(url=u).read()