diff --git a/binary_search_tool/android/generate_cmd.sh b/binary_search_tool/android/generate_cmd.sh
new file mode 100755
index 0000000..eaae738
--- /dev/null
+++ b/binary_search_tool/android/generate_cmd.sh
@@ -0,0 +1,41 @@
+#!/bin/bash -u
+
+# Copyright 2018 The Chromium OS 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 extracts command line options to build bad item.
+# The generated script will be used by pass level bisection.
+#
+
+source android/common.sh
+
+abs_path=$1
+
+# The item will be `-o relative-path-to-object `, which will be used
+# for seeking command in populate log.
+# We care about the `-o` at the beginning and ` ` at the end are necessary,
+# so that we can get build command for exact this object file.
+# Example: prebuilt/../clang++ -O3 -MF obj1.o.d -o obj.o obj.cpp
+# We should count this command as one to build obj.o, not obj1.o.d.
+real_path=$(realpath --relative-to="${BISECT_WORK_BUILD}" "${abs_path}")
+item="-o $real_path "
+
+populate_log=${BISECT_BAD_BUILD}/_POPULATE_LOG
+
+output='#!/bin/bash -u\n'
+output+='source android/common.sh\n'
+
+result=$(egrep -m 1 -- "${item}" ${populate_log})
+
+# Remove `:` after cd command
+result=$(sed 's/cd\:/cd/g' <<< ${result})
+
+# Add environment variable which helps pass level bisection
+result=$(sed 's/ \-o / $LIMIT_FLAGS \-o /g' <<< ${result})
+
+output+=${result}
+
+echo -e "${output}" > android/cmd_script.sh
+
+echo 'Script created as android/cmd_script.sh'
diff --git a/binary_search_tool/binary_search_state.py b/binary_search_tool/binary_search_state.py
index 1906525..645e613 100755
--- a/binary_search_tool/binary_search_state.py
+++ b/binary_search_tool/binary_search_state.py
@@ -1,4 +1,9 @@
 #!/usr/bin/env python2
+
+# Copyright 2018 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 """The binary search wrapper."""
 
 from __future__ import print_function
@@ -63,8 +68,8 @@
   """The binary search state class."""
 
   def __init__(self, get_initial_items, switch_to_good, switch_to_bad,
-               test_setup_script, test_script, incremental, prune, iterations,
-               prune_iterations, verify, file_args, verbose):
+               test_setup_script, test_script, incremental, prune, pass_bisect,
+               iterations, prune_iterations, verify, file_args, verbose):
     """BinarySearchState constructor, see Run for full args documentation."""
     self.get_initial_items = get_initial_items
     self.switch_to_good = switch_to_good
@@ -73,6 +78,7 @@
     self.test_script = test_script
     self.incremental = incremental
     self.prune = prune
+    self.pass_bisect = pass_bisect
     self.iterations = iterations
     self.prune_iterations = prune_iterations
     self.verify = verify
@@ -270,6 +276,26 @@
       # FIXME: Do we need to Convert the currently good items to bad
       self.PopulateItemsUsingList(new_all_items)
 
+    # If pass level bisecting is set, generate a script which contains command
+    # line options to rebuild bad item.
+    if self.pass_bisect:
+      assert not self.prune, 'Prune must be false if pass_bisect is set.'
+      status = self.GenerateBadCommandScript(self.found_items)
+      if status == 0:
+        self.l.LogOutput('Command script generated.')
+      else:
+        raise RuntimeError('Error while generating command script.')
+
+  def GenerateBadCommandScript(self, bad_items):
+    assert len(bad_items) == 1, 'Pruning is off, but number of bad items' \
+                                'found was not 1.'
+    item = list(bad_items)[0]
+
+    command = '%s %s' % (self.pass_bisect, item)
+    ret, _, _ = self.ce.RunCommandWExceptionCleanup(command,
+                  print_to_console=self.verbose)
+    return ret
+
   def DoBinarySearch(self):
     """Perform single iteration of binary search."""
     # If in resume mode don't reset search_cycles
@@ -467,6 +493,7 @@
         'test_script': None,
         'incremental': True,
         'prune': False,
+        'pass_bisect': None,
         'iterations': 50,
         'prune_iterations': 100,
         'verify': True,
@@ -498,6 +525,7 @@
         test_setup_script=None,
         iterations=50,
         prune=False,
+        pass_bisect=None,
         noincremental=False,
         file_args=False,
         verify=True,
@@ -520,6 +548,9 @@
     prune: If False the binary search tool will stop when the first bad item is
            found. Otherwise then binary search tool will continue searching
            until all bad items are found (or prune_iterations is reached).
+    pass_bisect: Script that takes single bad item from POPULATE_BAD and
+                 returns the compiler command used to generate the bad item.
+                 Requires that 'prune' be set to False.
     noincremental: Whether to send "diffs" of good/bad items to switch scripts.
     file_args: If True then arguments to switch scripts will be a file name
                containing a newline separated list of the items to switch.
@@ -532,18 +563,36 @@
   Returns:
     0 for success, error otherwise
   """
+  # Notice that all the argument checks are in the Run() function rather than
+  # in the Main() function. It is not common to do so but some wrappers are
+  # going to call Run() directly and bypass checks in Main() function.
   if resume:
+    logger.GetLogger().LogOutput('Resuming from %s' % STATE_FILE)
     bss = BinarySearchState.LoadState()
     if not bss:
       logger.GetLogger().LogOutput(
           '%s is not a valid binary_search_tool state file, cannot resume!' %
           STATE_FILE)
       return 1
+    logger.GetLogger().LogOutput('Note: resuming from previous state, '
+                                 'ignoring given options and loading saved '
+                                 'options instead.')
   else:
+    if not (get_initial_items and switch_to_good and
+            switch_to_bad and test_script):
+      logger.GetLogger().LogOutput('The following options are required: '
+                                   '[-i, -g, -b, -t] | [-r]')
+      return 1
+    if pass_bisect and prune:
+      logger.GetLogger().LogOutput('"--pass_bisect" only works when '
+                                   '"--prune" is set to be False.')
+      return 1
     switch_to_good = _CanonicalizeScript(switch_to_good)
     switch_to_bad = _CanonicalizeScript(switch_to_bad)
     if test_setup_script:
       test_setup_script = _CanonicalizeScript(test_setup_script)
+    if pass_bisect:
+      pass_bisect = _CanonicalizeScript(pass_bisect)
     test_script = _CanonicalizeScript(test_script)
     get_initial_items = _CanonicalizeScript(get_initial_items)
     incremental = not noincremental
@@ -552,8 +601,8 @@
 
     bss = BinarySearchState(get_initial_items, switch_to_good, switch_to_bad,
                             test_setup_script, test_script, incremental, prune,
-                            iterations, prune_iterations, verify, file_args,
-                            verbose)
+                            pass_bisect, iterations, prune_iterations, verify,
+                            file_args, verbose)
     bss.DoVerify()
 
   try:
@@ -577,18 +626,6 @@
   logger.GetLogger().LogOutput(' '.join(argv))
   options = parser.parse_args(argv)
 
-  if not (options.get_initial_items and options.switch_to_good and
-          options.switch_to_bad and options.test_script) and not options.resume:
-    parser.print_help()
-    return 1
-
-  if options.resume:
-    logger.GetLogger().LogOutput('Resuming from %s' % STATE_FILE)
-    if len(argv) > 1:
-      logger.GetLogger().LogOutput(('Note: resuming from previous state, '
-                                    'ignoring given options and loading saved '
-                                    'options instead.'))
-
   # Get dictionary of all options
   args = vars(options)
   return Run(**args)
diff --git a/binary_search_tool/common.py b/binary_search_tool/common.py
index 945270b..1d950ce 100644
--- a/binary_search_tool/common.py
+++ b/binary_search_tool/common.py
@@ -1,3 +1,7 @@
+# Copyright 2018 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 """Common config and logic for binary search tool
 
 This module serves two main purposes:
@@ -142,35 +146,35 @@
       '-i',
       '--get_initial_items',
       dest='get_initial_items',
-      help=('Script to run to get the initial objects. '
-            'If your script requires user input '
-            'the --verbose option must be used'))
+      help='Script to run to get the initial objects. '
+           'If your script requires user input '
+           'the --verbose option must be used')
   args.AddArgument(
       '-g',
       '--switch_to_good',
       dest='switch_to_good',
-      help=('Script to run to switch to good. '
-            'If your switch script requires user input '
-            'the --verbose option must be used'))
+      help='Script to run to switch to good. '
+           'If your switch script requires user input '
+           'the --verbose option must be used')
   args.AddArgument(
       '-b',
       '--switch_to_bad',
       dest='switch_to_bad',
-      help=('Script to run to switch to bad. '
-            'If your switch script requires user input '
-            'the --verbose option must be used'))
+      help='Script to run to switch to bad. '
+           'If your switch script requires user input '
+           'the --verbose option must be used')
   args.AddArgument(
       '-I',
       '--test_setup_script',
       dest='test_setup_script',
-      help=('Optional script to perform building, flashing, '
-            'and other setup before the test script runs.'))
+      help='Optional script to perform building, flashing, '
+           'and other setup before the test script runs.')
   args.AddArgument(
       '-t',
       '--test_script',
       dest='test_script',
-      help=('Script to run to test the '
-            'output after packages are built.'))
+      help='Script to run to test the '
+           'output after packages are built.')
   # No input (evals to False),
   # --prune (evals to True),
   # --prune=False,
@@ -184,8 +188,17 @@
       default=False,
       type=StrToBool,
       metavar='bool',
-      help=('If True, continue until all bad items are found. '
-            'Defaults to False.'))
+      help='If True, continue until all bad items are found. '
+            'Defaults to False.')
+  args.AddArgument(
+      '-P',
+      '--pass_bisect',
+      dest='pass_bisect',
+      default=None,
+      help='Script to generate another script for pass level bisect, '
+           'which contains command line options to build bad item.'
+           'For now it only supports one single bad item, so to use it, '
+           'prune must be set to false.')
   # No input (evals to False),
   # --noincremental (evals to True),
   # --noincremental=False,
@@ -199,8 +212,8 @@
       default=False,
       type=StrToBool,
       metavar='bool',
-      help=('If True, don\'t propagate good/bad changes '
-            'incrementally. Defaults to False.'))
+      help='If True, don\'t propagate good/bad changes '
+           'incrementally. Defaults to False.')
   # No input (evals to False),
   # --file_args (evals to True),
   # --file_args=False,
@@ -214,8 +227,8 @@
       default=False,
       type=StrToBool,
       metavar='bool',
-      help=('Whether to use a file to pass arguments to scripts. '
-            'Defaults to False.'))
+      help='Whether to use a file to pass arguments to scripts. '
+           'Defaults to False.')
   # No input (evals to True),
   # --verify (evals to True),
   # --verify=False,
@@ -228,8 +241,8 @@
       default=True,
       type=StrToBool,
       metavar='bool',
-      help=('Whether to run verify iterations before searching. '
-            'Defaults to True.'))
+      help='Whether to run verify iterations before searching. '
+           'Defaults to True.')
   args.AddArgument(
       '-N',
       '--prune_iterations',
@@ -256,6 +269,6 @@
       '--resume',
       dest='resume',
       action='store_true',
-      help=('Resume bisection tool execution from state file.'
-            'Useful if the last bisection was terminated '
-            'before it could properly finish.'))
+      help='Resume bisection tool execution from state file.'
+           'Useful if the last bisection was terminated '
+           'before it could properly finish.')