Index: head/share/mk/bsd.dep.mk
===================================================================
--- head/share/mk/bsd.dep.mk
+++ head/share/mk/bsd.dep.mk
@@ -128,18 +128,18 @@
 .for _D in ${_DSRC:R}
 DHDRS+=	${_D}.h
 ${_D}.h: ${_DSRC}
-	${DTRACE} -xnolibs -h -s ${.ALLSRC}
+	${DTRACE} ${DTRACEFLAGS} -h -s ${.ALLSRC}
 SRCS:=	${SRCS:S/^${_DSRC}$//}
 OBJS+=	${_D}.o
 CLEANFILES+= ${_D}.h ${_D}.o
 ${_D}.o: ${_DSRC} ${OBJS:S/^${_D}.o$//}
-	${DTRACE} -xnolibs -G -o ${.TARGET} -s ${.ALLSRC}
+	${DTRACE} ${DTRACEFLAGS} -G -o ${.TARGET} -s ${.ALLSRC}
 .if defined(LIB)
 CLEANFILES+= ${_D}.So ${_D}.po
 ${_D}.So: ${_DSRC} ${SOBJS:S/^${_D}.So$//}
-	${DTRACE} -xnolibs -G -o ${.TARGET} -s ${.ALLSRC}
+	${DTRACE} ${DTRACEFLAGS} -G -o ${.TARGET} -s ${.ALLSRC}
 ${_D}.po: ${_DSRC} ${POBJS:S/^${_D}.po$//}
-	${DTRACE} -xnolibs -G -o ${.TARGET} -s ${.ALLSRC}
+	${DTRACE} ${DTRACEFLAGS} -G -o ${.TARGET} -s ${.ALLSRC}
 .endif
 .endfor
 .endfor
Index: head/share/mk/sys.mk
===================================================================
--- head/share/mk/sys.mk
+++ head/share/mk/sys.mk
@@ -62,17 +62,18 @@
 .endif
 PO_CFLAGS	?=	${CFLAGS}
 
+# cp(1) is used to copy source files to ${.OBJDIR}, make sure it can handle
+# read-only files as non-root by passing -f.
+CP		?=	cp -f
+
+CPP		?=	cpp
+
 # C Type Format data is required for DTrace
 CTFFLAGS	?=	-L VERSION
 
 CTFCONVERT	?=	ctfconvert
 CTFMERGE	?=	ctfmerge
 
-# cp(1) is used to copy source files to ${.OBJDIR}, make sure it can handle
-# read-only files as non-root by passing -f.
-CP		?=	cp -f
-
-DTRACE		?=	dtrace
 .if defined(CFLAGS) && (${CFLAGS:M-g} != "")
 CTFFLAGS	+=	-g
 .endif
@@ -81,7 +82,8 @@
 CXXFLAGS	?=	${CFLAGS:N-std=*:N-Wnested-externs:N-W*-prototypes:N-Wno-pointer-sign:N-Wold-style-definition}
 PO_CXXFLAGS	?=	${CXXFLAGS}
 
-CPP		?=	cpp
+DTRACE		?=	dtrace
+DTRACEFLAGS	?=	-C -x nolibs
 
 .if empty(.MAKEFLAGS:M-s)
 ECHO		?=	echo