--- a/client.mk
+++ b/client.mk
@@ -7,18 +7,16 @@
 # Defines main targets for driving the Firefox build system.
 #
 # This make file should not be invoked directly. Instead, use
 # `mach` (likely `mach build`) for invoking the build system.
 #
 # Options:
 #   MOZ_OBJDIR           - Destination object directory
 #   MOZ_MAKE_FLAGS       - Flags to pass to $(MAKE)
-#   MOZ_PREFLIGHT_ALL    - Makefiles to run before building.
-#   MOZ_POSTFLIGHT_ALL   - Makefiles to run after building.
 #
 #######################################################################
 # Defines
 
 comma := ,
 
 ifdef MACH
 ifndef NO_BUILDSTATUS_MESSAGES
@@ -148,27 +146,16 @@ all build clean distclean export libs in
 ifneq (,$(strip $(MOZCONFIG_OUT_FILTERED)))
 	$(info Adding client.mk options from $(FOUND_MOZCONFIG):)
 	$(foreach line,$(MOZCONFIG_OUT_FILTERED),$(info $(NULL) $(NULL) $(NULL) $(NULL) $(subst ||, ,$(line))))
 endif
 
 # helper target for mobile
 build_and_deploy: build package install
 
-#####################################################
-# Preflight, before building any project
-
-ifdef MOZ_PREFLIGHT_ALL
-build preflight_all::
-	set -e; \
-	for mkfile in $(MOZ_PREFLIGHT_ALL); do \
-	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
-	done
-endif
-
 # In automation, manage an sccache daemon. The starting of the server
 # needs to be in a make file so sccache inherits the jobserver.
 ifdef MOZBUILD_MANAGE_SCCACHE_DAEMON
 build::
 	# Terminate any sccache server that might still be around.
 	-$(MOZBUILD_MANAGE_SCCACHE_DAEMON) --stop-server > /dev/null 2>&1
 	# Start a new server, ensuring it gets the jobserver file descriptors
 	# from make (but don't use the + prefix when make -n is used, so that
@@ -287,44 +274,31 @@ build::  $(OBJDIR)/Makefile $(OBJDIR)/co
 
 ####################################
 # Other targets
 
 # Pass these target onto the real build system
 $(OBJDIR_TARGETS):: $(OBJDIR)/Makefile $(OBJDIR)/config.status
 	+$(MOZ_MAKE) $@
 
-####################################
-# Postflight, after building all projects
-
 ifdef MOZ_AUTOMATION
 build::
 	$(MAKE) -f $(TOPSRCDIR)/client.mk automation/build
 endif
 
 ifdef MOZBUILD_MANAGE_SCCACHE_DAEMON
 build::
 	# Terminate sccache server. This prints sccache stats.
 	-$(MOZBUILD_MANAGE_SCCACHE_DAEMON) --stop-server
 endif
 
-ifdef MOZ_POSTFLIGHT_ALL
-build postflight_all::
-	set -e; \
-	for mkfile in $(MOZ_POSTFLIGHT_ALL); do \
-	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
-	done
-endif
-
 echo-variable-%:
 	@echo $($*)
 
 # 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: \
     build \
     configure \
-    preflight_all \
-    postflight_all \
     $(OBJDIR_TARGETS)