deleted file mode 100644
--- a/build/automation-build.mk
+++ /dev/null
@@ -1,67 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-include $(MOZILLA_DIR)/build/binary-location.mk
-
-browser_path := '"$(browser_path)"'
-
-_PROFILE_DIR = $(TARGET_DEPTH)/_profile/pgo
-
-ABSOLUTE_TOPSRCDIR = $(abspath $(MOZILLA_DIR))
-_CERTS_SRC_DIR = $(ABSOLUTE_TOPSRCDIR)/build/pgo/certs
-
-AUTOMATION_PPARGS = 	\
-			-DBROWSER_PATH=$(browser_path) \
-			-DXPC_BIN_PATH='"$(DIST)/bin"' \
-			-DBIN_SUFFIX='"$(BIN_SUFFIX)"' \
-			-DPROFILE_DIR='"$(_PROFILE_DIR)"' \
-			-DCERTS_SRC_DIR='"$(_CERTS_SRC_DIR)"' \
-			-DPERL='"$(PERL)"' \
-			$(NULL)
-
-ifeq ($(OS_ARCH),Darwin)
-AUTOMATION_PPARGS += -DIS_MAC=1
-else
-AUTOMATION_PPARGS += -DIS_MAC=0
-endif
-
-ifeq ($(OS_ARCH),Linux)
-AUTOMATION_PPARGS += -DIS_LINUX=1
-else
-AUTOMATION_PPARGS += -DIS_LINUX=0
-endif
-
-ifeq ($(host_os), cygwin)
-AUTOMATION_PPARGS += -DIS_CYGWIN=1
-endif
-
-ifeq ($(ENABLE_TESTS), 1)
-AUTOMATION_PPARGS += -DIS_TEST_BUILD=1
-else
-AUTOMATION_PPARGS += -DIS_TEST_BUILD=0
-endif
-
-ifeq ($(MOZ_DEBUG), 1)
-AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=1
-else
-AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=0
-endif
-
-ifdef MOZ_CRASHREPORTER
-AUTOMATION_PPARGS += -DCRASHREPORTER=1
-else
-AUTOMATION_PPARGS += -DCRASHREPORTER=0
-endif
-
-ifdef MOZ_ASAN
-AUTOMATION_PPARGS += -DIS_ASAN=1
-else
-AUTOMATION_PPARGS += -DIS_ASAN=0
-endif
-
-automation.py: $(MOZILLA_DIR)/build/automation.py.in $(MOZILLA_DIR)/build/automation-build.mk
-	$(call py_action,preprocessor, \
-	$(AUTOMATION_PPARGS) $(DEFINES) $(ACDEFINES) $< -o $@)
-
-GARBAGE += automation.py automation.pyc

--- a/build/automation.py.in
+++ b/build/automation.py.in
@@ -48,17 +48,16 @@ from mozscreenshot import printstatus, d
 #expand _IS_LINUX = __IS_LINUX__ != 0
 #ifdef IS_CYGWIN
 #expand _IS_CYGWIN = __IS_CYGWIN__ == 1
 #else
 _IS_CYGWIN = False
 #endif
 #expand _BIN_SUFFIX = __BIN_SUFFIX__
 
-#expand _DEFAULT_APP = "./" + __BROWSER_PATH__
 #expand _CERTS_SRC_DIR = __CERTS_SRC_DIR__
 #expand _IS_TEST_BUILD = __IS_TEST_BUILD__
 #expand _IS_DEBUG_BUILD = __IS_DEBUG_BUILD__
 #expand _CRASHREPORTER = __CRASHREPORTER__ == 1
 #expand _IS_ASAN = __IS_ASAN__ == 1
 
 
 if _IS_WIN32:
@@ -94,17 +93,16 @@ class Automation(object):
   IS_WIN32 = _IS_WIN32
   IS_MAC = _IS_MAC
   IS_LINUX = _IS_LINUX
   IS_CYGWIN = _IS_CYGWIN
   BIN_SUFFIX = _BIN_SUFFIX
 
   UNIXISH = not IS_WIN32 and not IS_MAC
 
-  DEFAULT_APP = _DEFAULT_APP
   CERTS_SRC_DIR = _CERTS_SRC_DIR
   IS_TEST_BUILD = _IS_TEST_BUILD
   IS_DEBUG_BUILD = _IS_DEBUG_BUILD
   CRASHREPORTER = _CRASHREPORTER
   IS_ASAN = _IS_ASAN
 
   # timeout, in seconds
   DEFAULT_TIMEOUT = 60.0
@@ -133,17 +131,16 @@ class Automation(object):
     return [
            "UNIXISH",
            "IS_WIN32",
            "IS_MAC",
            "log",
            "runApp",
            "Process",
            "DIST_BIN",
-           "DEFAULT_APP",
            "CERTS_SRC_DIR",
            "environment",
            "IS_TEST_BUILD",
            "IS_DEBUG_BUILD",
            "DEFAULT_TIMEOUT",
           ]
 
   class Process(subprocess.Popen):

new file mode 100644
--- /dev/null
+++ b/build/gen_automation.py
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distibuted with this
+# file, You can obtain one at http://mozilla.og/MPL/2.0/.
+
+import sys
+import buildconfig
+from mozbuild.preprocessor import Preprocessor
+
+
+def main(output, input_file):
+    pp = Preprocessor()
+    pp.context.update(buildconfig.defines['ALLDEFINES'])
+
+    substs = buildconfig.substs
+
+    # Substs taken verbatim.
+    substs_vars = (
+        'BIN_SUFFIX',
+    )
+    for var in substs_vars:
+        pp.context[var] = '"%s"' % substs[var]
+
+    # Derived values.
+    for key, condition in (
+            ('IS_MAC', substs['OS_ARCH'] == 'Darwin'),
+            ('IS_LINUX', substs['OS_ARCH'] == 'Linux'),
+            ('IS_TEST_BUILD', substs.get('ENABLE_TESTS') == '1'),
+            ('IS_DEBUG_BUILD', substs.get('MOZ_DEBUG') == '1'),
+            ('CRASHREPORTER', substs.get('MOZ_CRASHREPORTER')),
+            ('IS_ASAN', substs.get('MOZ_ASAN'))):
+        if condition:
+            pp.context[key] = '1'
+        else:
+            pp.context[key] = '0'
+
+    pp.context.update({
+        'XPC_BIN_PATH': '"%s/dist/bin"' % buildconfig.topobjdir,
+        'CERTS_SRC_DIR': '"%s/build/pgo/certs"' % buildconfig.topsrcdir,
+    })
+
+    pp.out = output
+    pp.do_include(input_file)
+
+
+if __name__ == '__main__':
+    main(*sys.agv[1:])

--- a/build/moz.build
+++ b/build/moz.build
@@ -91,16 +91,30 @@ if CONFIG['MOZ_APP_BASENAME']:
     if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'android' and CONFIG['MOZ_UPDATER']:
         FINAL_TARGET_PP_FILES += ['update-settings.ini']
 
     GENERATED_FILES += ['application.ini.h']
     appini = GENERATED_FILES['application.ini.h']
     appini.script = 'appini_header.py'
     appini.inputs = ['!application.ini']
 
+if CONFIG['ENABLE_TESTS']:
+    GENERATED_FILES += ['automation.py']
+    auto = GENERATED_FILES['automation.py']
+    auto.script = 'gen_automation.py'
+    auto.inputs = ['automation.py.in']
+
+    TEST_HARNESS_FILES.reftest += [
+        '!automation.py',
+    ]
+
+    TEST_HARNESS_FILES.testing.mochitest += [
+        '!automation.py',
+    ]
+
 # NOTE: Keep .gdbinit in the topsrcdir for people who run gdb from the topsrcdir.
 OBJDIR_FILES += ['/.gdbinit']
 
 # Put a .lldbinit in the bin directory and the objdir, to be picked up
 # automatically by LLDB when we debug executables using either of those two
 # directories as the current working directory.  The .lldbinit file will
 # load $(topsrcdir)/.lldbinit, which is where the actual debugging commands are.
 DEFINES['topsrcdir'] = TOPSRCDIR

--- a/layout/tools/reftest/Makefile.in
+++ b/layout/tools/reftest/Makefile.in
@@ -2,17 +2,13 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 _DEST_DIR = $(DEPTH)/_tests/reftest
 
 include $(topsrcdir)/config/rules.mk
 
-# We're installing to _tests/reftest
-TARGET_DEPTH = ../..
-include $(topsrcdir)/build/automation-build.mk
-
 # copy harness and the reftest extension bits to $(_DEST_DIR)
 # This needs to happen after jar.mn handling from rules.mk included above.
 # The order of the :: rules ensures that.
 libs::
 	(cd $(DIST)/xpi-stage && tar $(TAR_CREATE_FLAGS) - reftest) | (cd $(_DEST_DIR) && tar -xf -)

--- a/layout/tools/reftest/moz.build
+++ b/layout/tools/reftest/moz.build
@@ -9,19 +9,17 @@ with Files('**'):
     SCHEDULES.exclusive = ['reftest']
 
 XPI_NAME = 'reftest'
 USE_EXTENSION_MANIFEST = True
 JAR_MANIFESTS += ['jar.mn']
 FINAL_TARGET_PP_FILES += ['install.rdf']
 FINAL_TARGET_FILES += ['bootstrap.js']
 
-GENERATED_FILES += ['automation.py']
 TEST_HARNESS_FILES.reftest += [
-    '!automation.py',
     '/build/mobile/remoteautomation.py',
     '/build/pgo/server-locations.txt',
     '/testing/mochitest/server.js',
     'mach_test_package_commands.py',
     'output.py',
     'reftest-preferences.js',
     'reftestcommandline.py',
     'remotereftest.py',

--- a/python/mozbuild/mozbuild/backend/tup.py
+++ b/python/mozbuild/mozbuild/backend/tup.py
@@ -564,17 +564,18 @@ class TupBackend(CommonBackend):
             extra_exports = {
                 'buildid.h': ['MOZ_BUILD_DATE'],
             }
             for f in obj.outputs:
                 exports = extra_exports.get(f)
                 if exports:
                     backend_file.export(exports)
 
-            if any(f in obj.outputs for f in ('source-repo.h', 'buildid.h')):
+            if any(f.endswith(('automation.py', 'source-repo.h', 'buildid.h'))
+                   for f in obj.outputs):
                 extra_outputs = [self._early_generated_files]
             else:
                 extra_outputs = [self._installed_files] if obj.required_for_compile else []
                 full_inputs += [self._early_generated_files]
 
             backend_file.rule(
                 display='python {script}:{method} -> [%o]'.format(script=obj.script, method=obj.method),
                 cmd=cmd,

--- a/testing/mochitest/Makefile.in
+++ b/testing/mochitest/Makefile.in
@@ -2,18 +2,14 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
 _DEST_DIR = $(DEPTH)/_tests/$(relativesrcdir)
 
 include $(topsrcdir)/config/rules.mk
-# We're installing to _tests/testing/mochitest, so this is the depth
-# necessary for relative objdir paths.
-TARGET_DEPTH = ../../..
-include $(topsrcdir)/build/automation-build.mk
 
 libs:: 
 	(cd $(DIST)/xpi-stage && tar $(TAR_CREATE_FLAGS) - mochijar) | (cd $(_DEST_DIR) && tar -xf -)
 
 $(_DEST_DIR):
 	$(NSINSTALL) -D $@

--- a/testing/mochitest/moz.build
+++ b/testing/mochitest/moz.build
@@ -21,22 +21,17 @@ FINAL_TARGET_PP_FILES += ['install.rdf']
 
 FINAL_TARGET_FILES += ['bootstrap.js']
 
 MOCHITEST_MANIFESTS += [
     'tests/MochiKit-1.4.2/tests/mochitest.ini',
 ]
 MOCHITEST_CHROME_MANIFESTS += ['chrome/chrome.ini']
 
-GENERATED_FILES += [
-    'automation.py',
-]
-
 TEST_HARNESS_FILES.testing.mochitest += [
-    '!automation.py',
     '/build/mobile/remoteautomation.py',
     '/build/pgo/server-locations.txt',
     '/build/sanitizers/lsan_suppressions.txt',
     '/build/sanitizers/ubsan_suppressions.txt',
     '/build/valgrind/cross-architecture.sup',
     '/build/valgrind/i386-pc-linux-gnu.sup',
     '/build/valgrind/x86_64-pc-linux-gnu.sup',
     '/netwerk/test/httpserver/httpd.js',