--- a/client.mk
+++ b/client.mk
@@ -169,16 +169,23 @@ CONFIGURES += $(TOPSRCDIR)/mozilla/confi
 CONFIGURES += $(TOPSRCDIR)/mozilla/js/src/configure
 
 #######################################################################
 # Rules
 
 # The default rule is build
 build::
 
+# These targets are candidates for auto-running client.py
+ifdef  ALWAYS_RUN_CLIENT_PY
+build::                      run_client_py
+configure::                  run_client_py
+endif
+
+
 # Print out any options loaded from mozconfig.
 all build clean depend distclean export libs install realclean::
 	@if test -f .mozconfig.out; then \
 	  cat .mozconfig.out; \
 	  rm -f .mozconfig.out; \
 	else true; \
 	fi
 
@@ -402,14 +409,19 @@ cleansrcdir:
 	          -o -exec test ! -d {}/CVS \; \) -prune \
 	          -o \( -name '*.[ao]' -o -name '*.so' \) -type f -print`; \
 	   build/autoconf/clean-config.sh; \
 	fi;
 
 echo-variable-%:
 	@echo $($*)
 
+checkout co: run_client_py
+
+run_client_py:
+	$(PYTHON) $(TOPSRCDIR)/client.py checkout $(CLIENT_PY_ARGS)
+
 # This makefile doesn't support parallel execution. It does pass
 # MOZ_MAKE_FLAGS to sub-make processes, so they will correctly execute
 # in parallel.
 .NOTPARALLEL:
 
-.PHONY: checkout real_checkout depend build profiledbuild maybe_clobber_profiledbuild export libs alldep install clean realclean distclean cleansrcdir pull_all build_all clobber clobber_all pull_and_build_all everything configure preflight_all preflight postflight postflight_all
+.PHONY: checkout co real_checkout depend build profiledbuild maybe_clobber_profiledbuild export libs alldep install clean realclean distclean cleansrcdir pull_all build_all clobber clobber_all pull_and_build_all everything configure preflight_all preflight postflight postflight_all