diff --git a/build/landmines.py b/build/landmines.py
new file mode 100755
index 0000000..031c309
--- /dev/null
+++ b/build/landmines.py
@@ -0,0 +1,148 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 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.
+
+"""
+This script runs every build as the first hook (See DEPS). If it detects that
+the build should be clobbered, it will delete the contents of the build
+directory.
+
+A landmine is tripped when a builder checks out a different revision, and the
+diff between the new landmines and the old ones is non-null. At this point, the
+build is clobbered.
+"""
+
+import difflib
+import errno
+import gyp_environment
+import logging
+import optparse
+import os
+import sys
+import subprocess
+import time
+
+import clobber
+import landmine_utils
+
+
+def get_build_dir(build_tool, src_dir, is_iphone=False):
+  """
+  Returns output directory absolute path dependent on build and targets.
+  Examples:
+    r'c:\b\build\slave\win\build\src\out'
+    '/mnt/data/b/build/slave/linux/build/src/out'
+    '/b/build/slave/ios_rel_device/build/src/xcodebuild'
+
+  Keep this function in sync with tools/build/scripts/slave/compile.py
+  """
+  ret = None
+  if build_tool == 'xcode':
+    ret = os.path.join(src_dir, 'xcodebuild')
+  elif build_tool in ['make', 'ninja', 'ninja-ios']:  # TODO: Remove ninja-ios.
+    if 'CHROMIUM_OUT_DIR' in os.environ:
+      output_dir = os.environ.get('CHROMIUM_OUT_DIR').strip()
+      if not output_dir:
+        raise Error('CHROMIUM_OUT_DIR environment variable is set but blank!')
+    else:
+      output_dir = landmine_utils.gyp_generator_flags().get('output_dir', 'out')
+    ret = os.path.join(src_dir, output_dir)
+  else:
+    raise NotImplementedError('Unexpected GYP_GENERATORS (%s)' % build_tool)
+  return os.path.abspath(ret)
+
+
+def clobber_if_necessary(new_landmines, src_dir):
+  """Does the work of setting, planting, and triggering landmines."""
+  out_dir = get_build_dir(landmine_utils.builder(), src_dir)
+  landmines_path = os.path.normpath(os.path.join(src_dir, '.landmines'))
+  try:
+    os.makedirs(out_dir)
+  except OSError as e:
+    if e.errno == errno.EEXIST:
+      pass
+
+  if os.path.exists(landmines_path):
+    with open(landmines_path, 'r') as f:
+      old_landmines = f.readlines()
+    if old_landmines != new_landmines:
+      old_date = time.ctime(os.stat(landmines_path).st_ctime)
+      diff = difflib.unified_diff(old_landmines, new_landmines,
+          fromfile='old_landmines', tofile='new_landmines',
+          fromfiledate=old_date, tofiledate=time.ctime(), n=0)
+      sys.stdout.write('Clobbering due to:\n')
+      sys.stdout.writelines(diff)
+      sys.stdout.flush()
+
+      clobber.clobber(out_dir)
+
+  # Save current set of landmines for next time.
+  with open(landmines_path, 'w') as f:
+    f.writelines(new_landmines)
+
+
+def process_options():
+  """Returns an options object containing the configuration for this script."""
+  parser = optparse.OptionParser()
+  parser.add_option(
+      '-s', '--landmine-scripts', action='append',
+      help='Path to the script which emits landmines to stdout. The target '
+           'is passed to this script via option -t. Note that an extra '
+           'script can be specified via an env var EXTRA_LANDMINES_SCRIPT.')
+  parser.add_option('-d', '--src-dir',
+      help='Path of the source root dir. Overrides the default location of the '
+           'source root dir when calculating the build directory.')
+  parser.add_option('-v', '--verbose', action='store_true',
+      default=('LANDMINES_VERBOSE' in os.environ),
+      help=('Emit some extra debugging information (default off). This option '
+          'is also enabled by the presence of a LANDMINES_VERBOSE environment '
+          'variable.'))
+
+  options, args = parser.parse_args()
+
+  if args:
+    parser.error('Unknown arguments %s' % args)
+
+  logging.basicConfig(
+      level=logging.DEBUG if options.verbose else logging.ERROR)
+
+  if options.src_dir:
+    if not os.path.isdir(options.src_dir):
+      parser.error('Cannot find source root dir at %s' % options.src_dir)
+    logging.debug('Overriding source root dir. Using: %s', options.src_dir)
+  else:
+    options.src_dir = \
+        os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+
+  if not options.landmine_scripts:
+    options.landmine_scripts = [os.path.join(options.src_dir, 'build',
+                                             'get_landmines.py')]
+
+  extra_script = os.environ.get('EXTRA_LANDMINES_SCRIPT')
+  if extra_script:
+    options.landmine_scripts += [extra_script]
+
+  return options
+
+
+def main():
+  options = process_options()
+
+  if landmine_utils.builder() in ('dump_dependency_json', 'eclipse'):
+    return 0
+
+  gyp_environment.SetEnvironment()
+
+  landmines = []
+  for s in options.landmine_scripts:
+    proc = subprocess.Popen([sys.executable, s], stdout=subprocess.PIPE)
+    output, _ = proc.communicate()
+    landmines.extend([('%s\n' % l.strip()) for l in output.splitlines()])
+  clobber_if_necessary(landmines, options.src_dir)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())