diff --git a/Makefile b/Makefile
index d4ce8ac..26271fd 100644
--- a/Makefile
+++ b/Makefile
@@ -54,12 +54,16 @@ ifeq ($(USE_ASM),1)
 	$(MAKE) -C $(ASMALLOC) jem SRCDIR=src
 endif
 ifeq ($(USE_JEM),1)
+ifeq ($(USE_SYSTEM_JEM),0)
 	$(MAKE) -C $(JEMALLOC)
 endif
+endif
 ifeq ($(USE_LUAJIT),1)
 	$(MAKE) -C $(LUAJIT) Q= TARGET_SONAME=libluajit.so CCDEBUG=-g
 endif
+ifeq ($(USE_SYSTEM_JANSSON),0)
 	$(MAKE) -C $(JANSSON)
+endif
 	$(MAKE) -C $(COMMON) CF=$(CF) EXT_CFLAGS="$(EXT_CFLAGS)"
 	$(MAKE) -C $(CF)
 	$(MAKE) -C $(MOD_LUA) CF=$(CF) COMMON=$(COMMON) LUA_CORE=$(LUA_CORE) EXT_CFLAGS="$(EXT_CFLAGS)" USE_LUAJIT=$(USE_LUAJIT) LUAJIT=$(LUAJIT)
@@ -174,16 +178,24 @@ mexp2: mexp1
 	$(MAKE) MEXP_PHASE=2 SRCDIR=$(realpath $(MEXP_DIR))/
 
 $(JANSSON)/configure:
+ifeq ($(USE_SYSTEM_JANSSON),0)
 	cd $(JANSSON) && autoreconf -i
+endif
 
 $(JANSSON)/Makefile: $(JANSSON)/configure
+ifeq ($(USE_SYSTEM_JANSSON),0)
 	cd $(JANSSON) && ./configure $(JANSSON_CONFIG_OPT)
+endif
 
 $(JEMALLOC)/configure:
+ifeq ($(USE_SYSTEM_JEM),0)
 	cd $(JEMALLOC) && autoconf
+endif
 
 $(JEMALLOC)/Makefile: $(JEMALLOC)/configure
+ifeq ($(USE_SYSTEM_JEM),0)
 	cd $(JEMALLOC) && ./configure $(JEM_CONFIG_OPT)
+endif
 
 $(LUAJIT)/src/luaconf.h: $(LUAJIT)/src/luaconf.h.orig
 	ln -s $(notdir $<) $@
diff --git a/make_in/Makefile.vars b/make_in/Makefile.vars
index efe3226..0b54701 100644
--- a/make_in/Makefile.vars
+++ b/make_in/Makefile.vars
@@ -31,6 +31,12 @@ ifeq ($(USE_ASM),1)
   EXT_CFLAGS += -DUSE_ASM
 endif
 
+# Use the system provided JEMalloc memory allocator? [By default, no.]
+USE_SYSTEM_JEM = 0
+
+# Use the system provided Jansson JSON API Library? [By default, no.]
+USE_SYSTEM_JANSSON = 0
+
 # Use the JEMalloc memory allocator?  [By default, yes.]
 USE_JEM = 1