diff --git a/contrib/tzcode/private.h b/contrib/tzcode/private.h
index 0bb70056a9d7..35d2444d4ec1 100644
--- a/contrib/tzcode/private.h
+++ b/contrib/tzcode/private.h
@@ -7,21 +7,8 @@
 /*
 ** This file is in the public domain, so clarified as of
 ** 1996-06-05 by Arthur David Olson.
-**
-** $FreeBSD$
 */
 
-/* Stuff moved from Makefile.inc to reduce clutter */
-#ifndef TM_GMTOFF
-#define TM_GMTOFF	tm_gmtoff
-#define TM_ZONE		tm_zone
-#define PCTS		1
-#define HAVE_LONG_DOUBLE 1
-#define	HAVE_UNISTD_H	1
-#define	LOCALE_HOME	_PATH_LOCALE
-#define TZDIR		"/usr/share/zoneinfo"
-#endif /* ndef TM_GMTOFF */
-
 /*
 ** This header is for use ONLY with the time conversion code.
 ** There is no guarantee that it will remain unchanged,
@@ -524,12 +511,6 @@ typedef unsigned long uintmax_t;
 # define restrict /* empty */
 #endif
 
-#if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
-# define ATTRIBUTE_PURE __attribute__ ((__pure__))
-#else
-# define ATTRIBUTE_PURE /* empty */
-#endif
-
 /*
 ** Workarounds for compilers/systems.
 */
diff --git a/contrib/tzcode/tzconfig.h b/contrib/tzcode/tzconfig.h
new file mode 100644
index 000000000000..730043b36526
--- /dev/null
+++ b/contrib/tzcode/tzconfig.h
@@ -0,0 +1,19 @@
+#ifndef TZCONFIG_H_INCLUDED
+#define TZCONFIG_H_INCLUDED
+
+#define TM_GMTOFF	tm_gmtoff
+#define TM_ZONE		tm_zone
+
+#define HAVE_GETTEXT	false
+#define HAVE_SYS_STAT_H	true
+#define HAVE_UNISTD_H	true
+#define HAVE_STDINT_H	true
+
+#define PCTS		1
+#define NETBSD_INSPIRED	0
+#define STD_INSPIRED	1
+#define HAVE_TZNAME	2
+#define USG_COMPAT	0
+#define ALTZONE		0
+
+#endif /* !TZCONFIG_H_INCLUDED */
diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index 45977b6b9005..f222565fd0bc 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -176,6 +176,8 @@ SRCS+=	__getosreldate.c \
 
 CFLAGS.arc4random.c= -I${SRCTOP}/sys -I${SRCTOP}/sys/crypto/chacha20
 
+CFLAGS.sysconf.c= -I${SRCTOP}/contrib/tzcode
+
 CFLAGS.dlfcn.c= ${RTLD_HDRS}
 CFLAGS.tls.c= ${RTLD_HDRS}
 
diff --git a/lib/libc/stdtime/Makefile.inc b/lib/libc/stdtime/Makefile.inc
index a7ef64650ba1..a55cbbb17e24 100644
--- a/lib/libc/stdtime/Makefile.inc
+++ b/lib/libc/stdtime/Makefile.inc
@@ -3,17 +3,20 @@
 
 .PATH:	${LIBC_SRCTOP}/stdtime ${SRCTOP}/contrib/tzcode
 
-SRCS+=	asctime.c difftime.c localtime.c strftime.c strptime.c timelocal.c \
-	time32.c
+TZCODE_SRCS=	asctime.c difftime.c localtime.c
+STDTIME_SRCS=	strftime.c strptime.c timelocal.c
+SRCS+=		${TZCODE_SRCS} ${STDTIME_SRCS} time32.c
 
-SYM_MAPS+= ${LIBC_SRCTOP}/stdtime/Symbol.map
+SYM_MAPS+=	${LIBC_SRCTOP}/stdtime/Symbol.map
 
-CFLAGS+= -I${SRCTOP}/contrib/tzcode -I${LIBC_SRCTOP}/stdtime
+.for src in ${TZCODE_SRCS} ${STDTIME_SRCS}
+CFLAGS.${src}+=	-I${SRCTOP}/contrib/tzcode -include tzconfig.h
+.endfor
+.for src in ${STDTIME_SRCS}
+CFLAGS.${src}+=	-I${LIBC_SRCTOP}/stdtime
+.endfor
 
-CFLAGS.localtime.c= -fwrapv
 CFLAGS.localtime.c+= -DALL_STATE -DTHREAD_SAFE
-CFLAGS.localtime.c+= -DHAVE_TZNAME=2 -DUSG_COMPAT=0 -DALTZONE=0
-CFLAGS.localtime.c+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
 .if ${MK_DETECT_TZ_CHANGES} != "no"
 CFLAGS.localtime.c+= -DDETECT_TZ_CHANGES
 .endif
diff --git a/usr.sbin/zdump/Makefile b/usr.sbin/zdump/Makefile
index 43e4edaae2b6..cbf7c5c566c8 100644
--- a/usr.sbin/zdump/Makefile
+++ b/usr.sbin/zdump/Makefile
@@ -6,7 +6,6 @@ PROG=	zdump
 MAN=	zdump.8
 SRCS=	zdump.c
 
-CFLAGS+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
-CFLAGS+= -I${SRCTOP}/contrib/tzcode
+CFLAGS+= -I${SRCTOP}/contrib/tzcode -include tzconfig.h
 
 .include <bsd.prog.mk>
diff --git a/usr.sbin/zic/Makefile b/usr.sbin/zic/Makefile
index a3eb6f7dadba..88d3f12c3016 100644
--- a/usr.sbin/zic/Makefile
+++ b/usr.sbin/zic/Makefile
@@ -6,7 +6,6 @@ PROG=	zic
 MAN=	zic.8
 SRCS=	zic.c
 
-CFLAGS+= -DNETBSD_INSPIRED=0 -DSTD_INSPIRED=1
-CFLAGS+= -I${SRCTOP}/contrib/tzcode
+CFLAGS+= -I${SRCTOP}/contrib/tzcode -include tzconfig.h
 
 .include <bsd.prog.mk>