diff --git a/tools/exec_util.py b/tools/exec_util.py
index 2692ed284..522f89d2f 100644
--- a/tools/exec_util.py
+++ b/tools/exec_util.py
@@ -5,14 +5,20 @@
 from subprocess import Popen, PIPE
 import sys
 
-def exec_cmd(cmd, path):
+def exec_cmd(cmd, path, input_file=None):
   """ Execute the specified command and return the result. """
   out = ''
   err = ''
   parts = cmd.split()
   try:
-    process = Popen(parts, cwd=path, stdout=PIPE, stderr=PIPE,
-                    shell=(sys.platform == 'win32'))
+    if not input_file:
+      process = Popen(parts, cwd=path, stdout=PIPE, stderr=PIPE,
+                      shell=(sys.platform == 'win32'))
+    else:
+      with open(input_file, 'rb') as f:
+        process = Popen(parts, cwd=path, stdout=PIPE, stderr=PIPE,
+                        stdin=f,
+                        shell=(sys.platform == 'win32'))
     out, err = process.communicate()
   except IOError, (errno, strerror):
     raise
diff --git a/tools/patch_updater.py b/tools/patch_updater.py
index a56e1e453..595d76a64 100644
--- a/tools/patch_updater.py
+++ b/tools/patch_updater.py
@@ -104,7 +104,7 @@ for patch in patches:
 
       # Apply the patch file.
       msg('Applying patch to %s' % patch_root_abs)
-      result = exec_cmd('patch -p0 < %s' % patch_file, patch_root_abs)
+      result = exec_cmd('patch -p0', patch_root_abs, patch_file)
       if result['err'] != '':
         raise Exception('Failed to apply patch file: %s' % result['err'])
       sys.stdout.write(result['out'])
@@ -117,12 +117,14 @@ for patch in patches:
     msg('Saving changes to %s' % patch_file)
     patch_paths_str = ' '.join(patch_paths)
     if src_is_git:
-      cmd = 'git diff --no-prefix --relative %s > %s' % \
-            (patch_paths_str, patch_file)
+      cmd = 'git diff --no-prefix --relative %s' % patch_paths_str
     else:
-      cmd = 'svn diff %s > %s' % (patch_paths_str, patch_file)
+      cmd = 'svn diff %s' % patch_paths_str
     result = exec_cmd(cmd, patch_root_abs)
     if result['err'] != '' and result['err'].find('warning:') != 0:
       raise Exception('Failed to create patch file: %s' % result['err'])
+    f = open(patch_file, 'wb')
+    f.write(result['out'])
+    f.close()
   else:
     raise Exception('Patch file does not exist: %s' % patch_file)