diff --git a/config/config.mk b/config/config.mk
index fae7c5c144bd..9ce437e31b8f 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -216,8 +216,8 @@ MOZ_UNICHARUTIL_LIBS = $(LIBXUL_DIST)/lib/$(LIB_PREFIX)unicharutil_s.$(LIB_SUFFI
 MOZ_WIDGET_SUPPORT_LIBS    = $(DIST)/lib/$(LIB_PREFIX)widgetsupport_s.$(LIB_SUFFIX)
 
 ifdef _MSC_VER
-CC_WRAPPER ?= $(PYTHON) -O $(topsrcdir)/build/cl.py
-CXX_WRAPPER ?= $(PYTHON) -O $(topsrcdir)/build/cl.py
+CC_WRAPPER = $(call py_action,cl)
+CXX_WRAPPER = $(call py_action,cl)
 endif # _MSC_VER
 
 CC := $(CC_WRAPPER) $(CC)
@@ -896,15 +896,3 @@ MOZ_GTK2_CFLAGS := -I$(topsrcdir)/widget/gtk/compat $(MOZ_GTK2_CFLAGS)
 endif
 
 DEFINES += -DNO_NSPR_10_SUPPORT
-
-# Run a named Python build action. The first argument is the name of the build
-# action. The second argument are the arguments to pass to the action (space
-# delimited arguments). e.g.
-#
-#   libs::
-#       $(call py_action,purge_manifests,_build_manifests/purge/foo.manifest)
-ifdef .PYMAKE
-py_action = %mozbuild.action.$(1) main $(2)
-else
-py_action = $(PYTHON) -m mozbuild.action.$(1) $(2)
-endif
diff --git a/config/makefiles/functions.mk b/config/makefiles/functions.mk
index 035443ffa34f..d97b604f9944 100644
--- a/config/makefiles/functions.mk
+++ b/config/makefiles/functions.mk
@@ -20,3 +20,15 @@ core_abspath = $(error core_abspath is unsupported, use $$(abspath) instead)
 core_realpath = $(error core_realpath is unsupported)
 
 core_winabspath = $(error core_winabspath is unsupported)
+
+# Run a named Python build action. The first argument is the name of the build
+# action. The second argument are the arguments to pass to the action (space
+# delimited arguments). e.g.
+#
+#   libs::
+#       $(call py_action,purge_manifests,_build_manifests/purge/foo.manifest)
+ifdef .PYMAKE
+py_action = %mozbuild.action.$(1) main $(2)
+else
+py_action = $(PYTHON) -m mozbuild.action.$(1) $(2)
+endif
diff --git a/js/src/build/cl.py b/js/src/build/cl.py
deleted file mode 100644
index 45e015eb4842..000000000000
--- a/js/src/build/cl.py
+++ /dev/null
@@ -1,114 +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/.
-
-import ctypes
-import os
-import sys
-
-from mozprocess.processhandler import ProcessHandlerMixin
-from mozbuild.makeutil import Makefile
-
-CL_INCLUDES_PREFIX = os.environ.get("CL_INCLUDES_PREFIX", "Note: including file:")
-
-GetShortPathName = ctypes.windll.kernel32.GetShortPathNameW
-GetLongPathName = ctypes.windll.kernel32.GetLongPathNameW
-
-
-# cl.exe likes to print inconsistent paths in the showIncludes output
-# (some lowercased, some not, with different directions of slashes),
-# and we need the original file case for make/pymake to be happy.
-# As this is slow and needs to be called a lot of times, use a cache
-# to speed things up.
-_normcase_cache = {}
-
-def normcase(path):
-    # Get*PathName want paths with backslashes
-    path = path.replace('/', os.sep)
-    dir = os.path.dirname(path)
-    # name is fortunately always going to have the right case,
-    # so we can use a cache for the directory part only.
-    name = os.path.basename(path)
-    if dir in _normcase_cache:
-        result = _normcase_cache[dir]
-    else:
-        path = ctypes.create_unicode_buffer(dir)
-        length = GetShortPathName(path, None, 0)
-        shortpath = ctypes.create_unicode_buffer(length)
-        GetShortPathName(path, shortpath, length)
-        length = GetLongPathName(shortpath, None, 0)
-        if length > len(path):
-            path = ctypes.create_unicode_buffer(length)
-        GetLongPathName(shortpath, path, length)
-        result = _normcase_cache[dir] = path.value
-    return os.path.join(result, name)
-
-
-def InvokeClWithDependencyGeneration(cmdline):
-    target = ""
-    # Figure out what the target is
-    for arg in cmdline:
-        if arg.startswith("-Fo"):
-            target = arg[3:]
-            break
-
-    if target == None:
-        print >>sys.stderr, "No target set" and sys.exit(1)
-
-    # Assume the source file is the last argument
-    source = cmdline[-1]
-    assert not source.startswith('-')
-
-    # The deps target lives here
-    depstarget = os.path.basename(target) + ".pp"
-
-    cmdline += ['-showIncludes']
-
-    mk = Makefile()
-    rule = mk.create_rule([target])
-    rule.add_dependencies([normcase(source)])
-
-    def on_line(line):
-        # cl -showIncludes prefixes every header with "Note: including file:"
-        # and an indentation corresponding to the depth (which we don't need)
-        if line.startswith(CL_INCLUDES_PREFIX):
-            dep = line[len(CL_INCLUDES_PREFIX):].strip()
-            # We can't handle pathes with spaces properly in mddepend.pl, but
-            # we can assume that anything in a path with spaces is a system
-            # header and throw it away.
-            dep = normcase(dep)
-            if ' ' not in dep:
-                rule.add_dependencies([dep])
-        else:
-            # Make sure we preserve the relevant output from cl. mozprocess
-            # swallows the newline delimiter, so we need to re-add it.
-            sys.stdout.write(line)
-            sys.stdout.write('\n')
-
-    # We need to ignore children because MSVC can fire up a background process
-    # during compilation. This process is cleaned up on its own. If we kill it,
-    # we can run into weird compilation issues.
-    p = ProcessHandlerMixin(cmdline, processOutputLine=[on_line],
-        ignore_children=True)
-    p.run()
-    p.processOutput()
-    ret = p.wait()
-
-    if ret != 0 or target == "":
-        sys.exit(ret)
-
-    depsdir = os.path.normpath(os.path.join(os.curdir, ".deps"))
-    depstarget = os.path.join(depsdir, depstarget)
-    if not os.path.isdir(depsdir):
-        try:
-            os.makedirs(depsdir)
-        except OSError:
-            pass # This suppresses the error we get when the dir exists, at the
-                 # cost of masking failure to create the directory.  We'll just
-                 # die on the next line though, so it's not that much of a loss.
-
-    with open(depstarget, "w") as f:
-        mk.dump(f)
-
-if __name__ == "__main__":
-    InvokeClWithDependencyGeneration(sys.argv[1:])
diff --git a/js/src/config/config.mk b/js/src/config/config.mk
index fae7c5c144bd..9ce437e31b8f 100644
--- a/js/src/config/config.mk
+++ b/js/src/config/config.mk
@@ -216,8 +216,8 @@ MOZ_UNICHARUTIL_LIBS = $(LIBXUL_DIST)/lib/$(LIB_PREFIX)unicharutil_s.$(LIB_SUFFI
 MOZ_WIDGET_SUPPORT_LIBS    = $(DIST)/lib/$(LIB_PREFIX)widgetsupport_s.$(LIB_SUFFIX)
 
 ifdef _MSC_VER
-CC_WRAPPER ?= $(PYTHON) -O $(topsrcdir)/build/cl.py
-CXX_WRAPPER ?= $(PYTHON) -O $(topsrcdir)/build/cl.py
+CC_WRAPPER = $(call py_action,cl)
+CXX_WRAPPER = $(call py_action,cl)
 endif # _MSC_VER
 
 CC := $(CC_WRAPPER) $(CC)
@@ -896,15 +896,3 @@ MOZ_GTK2_CFLAGS := -I$(topsrcdir)/widget/gtk/compat $(MOZ_GTK2_CFLAGS)
 endif
 
 DEFINES += -DNO_NSPR_10_SUPPORT
-
-# Run a named Python build action. The first argument is the name of the build
-# action. The second argument are the arguments to pass to the action (space
-# delimited arguments). e.g.
-#
-#   libs::
-#       $(call py_action,purge_manifests,_build_manifests/purge/foo.manifest)
-ifdef .PYMAKE
-py_action = %mozbuild.action.$(1) main $(2)
-else
-py_action = $(PYTHON) -m mozbuild.action.$(1) $(2)
-endif
diff --git a/js/src/config/makefiles/functions.mk b/js/src/config/makefiles/functions.mk
index 035443ffa34f..d97b604f9944 100644
--- a/js/src/config/makefiles/functions.mk
+++ b/js/src/config/makefiles/functions.mk
@@ -20,3 +20,15 @@ core_abspath = $(error core_abspath is unsupported, use $$(abspath) instead)
 core_realpath = $(error core_realpath is unsupported)
 
 core_winabspath = $(error core_winabspath is unsupported)
+
+# Run a named Python build action. The first argument is the name of the build
+# action. The second argument are the arguments to pass to the action (space
+# delimited arguments). e.g.
+#
+#   libs::
+#       $(call py_action,purge_manifests,_build_manifests/purge/foo.manifest)
+ifdef .PYMAKE
+py_action = %mozbuild.action.$(1) main $(2)
+else
+py_action = $(PYTHON) -m mozbuild.action.$(1) $(2)
+endif
diff --git a/build/cl.py b/python/mozbuild/mozbuild/action/cl.py
similarity index 94%
rename from build/cl.py
rename to python/mozbuild/mozbuild/action/cl.py
index 45e015eb4842..0d7cc55d8b53 100644
--- a/build/cl.py
+++ b/python/mozbuild/mozbuild/action/cl.py
@@ -52,8 +52,9 @@ def InvokeClWithDependencyGeneration(cmdline):
             target = arg[3:]
             break
 
-    if target == None:
-        print >>sys.stderr, "No target set" and sys.exit(1)
+    if target is None:
+        print >>sys.stderr, "No target set"
+        return 1
 
     # Assume the source file is the last argument
     source = cmdline[-1]
@@ -95,7 +96,7 @@ def InvokeClWithDependencyGeneration(cmdline):
     ret = p.wait()
 
     if ret != 0 or target == "":
-        sys.exit(ret)
+        return ret
 
     depsdir = os.path.normpath(os.path.join(os.curdir, ".deps"))
     depstarget = os.path.join(depsdir, depstarget)
@@ -110,5 +111,10 @@ def InvokeClWithDependencyGeneration(cmdline):
     with open(depstarget, "w") as f:
         mk.dump(f)
 
+    return 0
+
+def main(args):
+    return InvokeClWithDependencyGeneration(args)
+
 if __name__ == "__main__":
-    InvokeClWithDependencyGeneration(sys.argv[1:])
+    sys.exit(main(sys.argv[1:]))