diff --git a/win_toolchain/package_from_installed.py b/win_toolchain/package_from_installed.py
new file mode 100644
index 000000000..0c4ee2a25
--- /dev/null
+++ b/win_toolchain/package_from_installed.py
@@ -0,0 +1,155 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+From a system-installed copy of the toolchain, packages all the required bits
+into a .zip file.
+
+It assumes default install locations for tools, in particular:
+- C:\Program Files (x86)\Microsoft Visual Studio 12.0\...
+- C:\Program Files (x86)\Windows Kits\8.0\...
+
+1. Start from a fresh Win7 VM image.
+2. Install VS Pro. Deselect everything except MFC.
+3. Install Windows 8 SDK. Select only the Windows SDK and Debugging Tools for
+Windows.
+4. Run this script, which will build a <sha1>.zip.
+
+Express is not yet supported by this script, but patches welcome (it's not too
+useful as the resulting zip can't be redistributed, and most will presumably
+have a Pro license anyway).
+"""
+
+import os
+import shutil
+import sys
+import tempfile
+import zipfile
+
+import get_toolchain_if_necessary
+import toolchain2013  # pylint: disable=F0401
+
+
+def BuildFileList():
+  result = []
+
+  # Subset of VS corresponding roughly to VC.
+  vs_path = r'C:\Program Files (x86)\Microsoft Visual Studio 12.0'
+  for path in [ 
+      'DIA SDK/bin',
+      'DIA SDK/idl',
+      'DIA SDK/include',
+      'DIA SDK/lib',
+      'VC/atlmfc',
+      'VC/bin',
+      'VC/crt',
+      'VC/include',
+      'VC/lib',
+      'VC/redist',
+      ('VC/redist/x86/Microsoft.VC120.CRT', 'sys32'),
+      ('VC/redist/x86/Microsoft.VC120.MFC', 'sys32'),
+      ('VC/redist/Debug_NonRedist/x86/Microsoft.VC120.DebugCRT', 'sys32'),
+      ('VC/redist/Debug_NonRedist/x86/Microsoft.VC120.DebugMFC', 'sys32'),
+      ('VC/redist/x64/Microsoft.VC120.CRT', 'sys64'),
+      ('VC/redist/x64/Microsoft.VC120.MFC', 'sys64'),
+      ('VC/redist/Debug_NonRedist/x64/Microsoft.VC120.DebugCRT', 'sys64'),
+      ('VC/redist/Debug_NonRedist/x64/Microsoft.VC120.DebugMFC', 'sys64'),
+      ]:
+    src = path[0] if isinstance(path, tuple) else path
+    combined = os.path.join(vs_path, src)
+    assert os.path.exists(combined) and os.path.isdir(combined)
+    for root, _, files in os.walk(combined):
+      for f in files:
+        final_from = os.path.normpath(os.path.join(root, f))
+        if isinstance(path, tuple):
+          result.append(
+              (final_from, os.path.normpath(os.path.join(path[1], f))))
+        else:
+          assert final_from.startswith(vs_path)
+          dest = final_from[len(vs_path) + 1:]
+          if dest.lower().endswith('\\xtree'):
+            # Patch for C4702 in xtree. http://crbug.com/346399.
+            (handle, patched) = tempfile.mkstemp()
+            with open(final_from, 'rb') as unpatched_f:
+              unpatched_contents = unpatched_f.read()
+            os.write(handle,
+                unpatched_contents.replace('warning(disable: 4127)',
+                                           'warning(disable: 4127 4702)'))
+            result.append((patched, dest))
+          else:
+            result.append((final_from, dest))
+
+  # Just copy the whole SDK.
+  sdk_path = r'C:\Program Files (x86)\Windows Kits\8.0'
+  for root, _, files in os.walk(sdk_path):
+    for f in files:
+      combined = os.path.normpath(os.path.join(root, f))
+      to = os.path.join('win8sdk', combined[len(sdk_path) + 1:])
+      result.append((combined, to))
+
+  # Generically drop all arm stuff that we don't need.
+  return [(f, t) for f, t in result if 'arm\\' not in f.lower()]
+
+
+def AddEnvSetup(files):
+  """We need to generate this file in the same way that the "from pieces"
+  script does, so pull that in here."""
+  tempdir = tempfile.mkdtemp()
+  os.makedirs(os.path.join(tempdir, 'win8sdk', 'bin'))
+  toolchain2013.GenerateSetEnvCmd(tempdir, True)
+  files.append((os.path.join(tempdir, 'win8sdk', 'bin', 'SetEnv.cmd'),
+                'win8sdk\\bin\\SetEnv.cmd'))
+
+
+def RenameToSha1(output):
+  """Determine the hash in the same way that the unzipper does to rename the
+  # .zip file."""
+  print 'Extracting to determine hash...'
+  tempdir = tempfile.mkdtemp()
+  old_dir = os.getcwd()
+  os.chdir(tempdir)
+  rel_dir = 'vs2013_files'
+  with zipfile.ZipFile(
+      os.path.join(old_dir, output), 'r', zipfile.ZIP_DEFLATED, True) as zf:
+    zf.extractall(rel_dir)
+  print 'Hashing...'
+  sha1 = get_toolchain_if_necessary.CalculateHash(rel_dir)
+  os.chdir(old_dir)
+  shutil.rmtree(tempdir)
+  final_name = sha1 + '.zip'
+  os.rename(output, final_name)
+  print 'Renamed %s to %s.' % (output, final_name)
+
+
+def main():
+  print 'Building file list...'
+  files = BuildFileList()
+
+  AddEnvSetup(files)
+
+  if False:
+    for f in files:
+      print f[0], '->', f[1]
+    return 0
+
+  output = 'out.zip'
+  if os.path.exists(output):
+    os.unlink(output)
+  count = 0
+  with zipfile.ZipFile(output, 'w', zipfile.ZIP_DEFLATED, True) as zf:
+    for disk_name, archive_name in files:
+      sys.stdout.write('\r%d/%d ...%s' % (count, len(files), disk_name[-40:]))
+      sys.stdout.flush()
+      count += 1
+      zf.write(disk_name, archive_name)
+  sys.stdout.write('\rWrote to %s.%s\n' % (output, ' '*50))
+  sys.stdout.flush()
+
+  RenameToSha1(output)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())