diff --git a/Tools/autotest/bisect-helper.py b/Tools/autotest/bisect-helper.py
new file mode 100755
index 0000000000..d0549ab0b7
--- /dev/null
+++ b/Tools/autotest/bisect-helper.py
@@ -0,0 +1,171 @@
+#!/usr/bin/env python
+
+'''
+A helper script for bisecting common problems when working with ArduPilot
+
+Bisect between a commit which builds and one which doesn't,
+finding the first commit which broke the build with a
+ specific failure:
+
+git bisect good a7647e77d9
+git bisect bad 153ad9539866f8d93a99e9998118bb090d2f747f
+cp -a Tools/autotest/bisect-helper.py /tmp
+git bisect run /tmp/bisect-helper.py --build \
+     --build-failure-string= \
+     "reference to 'OpticalFlow' is ambiguous"
+
+Work out who killed bebop:
+cp -a Tools/autotest/bisect-helper.py /tmp
+git bisect good a7647e77d9 &&
+  git bisect bad 153ad9539866f8d93a99e9998118bb090d2f747f &&
+  git bisect run /tmp/bisect-helper.py --build \
+    --waf-configure-arg="--board bebop"
+
+'''
+
+import optparse
+import os
+import subprocess
+import shlex
+import sys
+import time
+
+
+class Bisect(object):
+    def __init__(self, opts):
+        self.opts = opts
+
+    def exit_skip(self):
+        self.progress("SKIP")
+        sys.exit(125)
+
+    def exit_pass(self):
+        self.progress("PASS")
+        sys.exit(0)
+
+    def exit_fail(self):
+        self.progress("FAIL")
+        sys.exit(1)
+
+    def progress(self, string):
+        '''pretty-print progress'''
+        print("BH: %s" % string)
+
+    def run_program(self, prefix, cmd_list):
+        '''copied in from build_binaries.py'''
+        '''run cmd_list, spewing and setting output in self'''
+        self.progress("Running (%s)" % " ".join(cmd_list))
+        p = subprocess.Popen(cmd_list,
+                             bufsize=1,
+                             stdin=None,
+                             close_fds=True,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.STDOUT)
+        self.program_output = ""
+        while True:
+            x = p.stdout.readline()
+            if len(x) == 0:
+                returncode = os.waitpid(p.pid, 0)
+                if returncode:
+                    break
+                    # select not available on Windows... probably...
+                time.sleep(0.1)
+                continue
+            self.program_output += x
+            x = x.rstrip()
+            print("%s: %s" % (prefix, x))
+        (_, status) = returncode
+        if status != 0:
+            self.progress("Process failed (%s)" %
+                          str(returncode))
+            raise subprocess.CalledProcessError(
+                returncode, cmd_list)
+
+    def build(self):
+        '''run ArduCopter build.  May exit with skip or fail'''
+        self.run_program("WAF-clean", ["./waf", "clean"])
+        cmd_configure = ["./waf", "configure"]
+        pieces = [shlex.split(x)
+                  for x in opts.waf_configure_args]
+        for piece in pieces:
+            cmd_configure.extend(piece)
+        self.run_program("WAF-configure", cmd_configure)
+        cmd_build = ["./waf", "build"]
+        pieces = [shlex.split(x)
+                  for x in opts.waf_build_args]
+        for piece in pieces:
+            cmd_build.extend(piece)
+        try:
+            self.run_program("WAF-build", cmd_build)
+        except subprocess.CalledProcessError as e:
+            # well, it definitely failed....
+            if opts.build_failure_string is not None:
+                if opts.build_failure_string in self.program_output:
+                    self.progress("Found relevant build failure")
+                    self.exit_fail()
+                # it failed, but not for the reason we're looking
+                # for...
+                self.exit_skip()
+            else:
+                self.exit_fail()
+
+
+class BisectBuild(Bisect):
+
+    def __init__(self, opts):
+        super(BisectBuild, self).__init__(opts)
+
+    def run(self):
+        self.build()  # may exit with skip or fail
+        self.exit_pass()
+
+
+class BisectCITest(Bisect):
+
+    def __init__(self, opts):
+        super(BisectCITest, self).__init__(opts)
+
+
+if __name__ == '__main__':
+
+    parser = optparse.OptionParser("bisect.py ")
+    parser.add_option("--build",
+                      action='store_true',
+                      default=False,
+                      help="Help bisect a build failure")
+    parser.add_option("--build-failure-string",
+                      type='string',
+                      default=None,
+                      help="If supplied, must be present in"
+                      "build output to count as a failure")
+
+    group_build = optparse.OptionGroup(parser, "Build options")
+    group_build.add_option("", "--waf-configure-arg",
+                           action="append",
+                           dest="waf_configure_args",
+                           type="string",
+                           default=["--board skyviper-v2450"],
+                           help="extra arguments to pass to"
+                           "waf in configure step")
+    group_build.add_option("", "--waf-build-arg",
+                           action="append",
+                           dest="waf_build_args",
+                           type="string",
+                           default=["--target bin/arducopter"],
+                           help="extra arguments to pass"
+                           "to waf in its build step")
+
+    parser.add_option_group(group_build)
+
+    (opts, args) = parser.parse_args()
+
+    if opts.build:
+        bisecter = BisectBuild(opts)
+    else:
+        bisecter = BisectCITest(opts)
+
+try:
+    bisecter.run()
+except Exception as e:
+    print("Caught exception in bisect-helper: %s" % str(e))
+    sys.exit(129)  # should abort the bisect process