Index: head/share/mk/bsd.dep.mk
===================================================================
--- head/share/mk/bsd.dep.mk
+++ head/share/mk/bsd.dep.mk
@@ -101,7 +101,7 @@
 CLEANFILES?=
 
 .for _S in ${SRCS:N*.[dhly]}
-OBJS_DEPEND_GUESS.${_S:R}.o+=	${_S}
+OBJS_DEPEND_GUESS.${_S:${OBJS_SRCS_FILTER:ts:}}.o+=	${_S}
 .endfor
 
 # Lexical analyzers
@@ -180,7 +180,7 @@
 DEPEND_FILTER=	C,/,_,g
 DEPENDSRCS=	${SRCS:M*.[cSC]} ${SRCS:M*.cxx} ${SRCS:M*.cpp} ${SRCS:M*.cc}
 .if !empty(DEPENDSRCS)
-DEPENDOBJS+=	${DEPENDSRCS:R:S,$,.o,}
+DEPENDOBJS+=	${DEPENDSRCS:${OBJS_SRCS_FILTER:ts:}:S,$,.o,}
 .endif
 DEPENDFILES_OBJS=	${DEPENDOBJS:O:u:${DEPEND_FILTER}:C/^/${DEPENDFILE}./}
 .if defined(_SKIP_DEPEND)
Index: head/share/mk/bsd.init.mk
===================================================================
--- head/share/mk/bsd.init.mk
+++ head/share/mk/bsd.init.mk
@@ -16,6 +16,10 @@
 .include <bsd.own.mk>
 .MAIN: all
 
+# This is used in bsd.{dep,lib,prog}.mk as ${OBJS_SRCS_FILTER:ts:}
+# Some makefiles may want T as well to avoid nested objdirs.
+OBJS_SRCS_FILTER+= R
+
 # Handle INSTALL_AS_USER here to maximize the chance that
 # it has final authority over fooOWN and fooGRP.
 .if ${MK_INSTALL_AS_USER} != "no"
Index: head/share/mk/bsd.lib.mk
===================================================================
--- head/share/mk/bsd.lib.mk
+++ head/share/mk/bsd.lib.mk
@@ -168,7 +168,7 @@
 .endif
 
 .if defined(LIB) && !empty(LIB) || defined(SHLIB_NAME)
-OBJS+=		${SRCS:N*.h:R:S/$/.o/}
+OBJS+=		${SRCS:N*.h:${OBJS_SRCS_FILTER:ts:}:S/$/.o/}
 CLEANFILES+=	${OBJS} ${STATICOBJS}
 .endif
 
@@ -437,13 +437,13 @@
 .if defined(LIB) && !empty(LIB)
 OBJS_DEPEND_GUESS+= ${SRCS:M*.h}
 .for _S in ${SRCS:N*.[hly]}
-OBJS_DEPEND_GUESS.${_S:R}.po+=	${_S}
+OBJS_DEPEND_GUESS.${_S:${OBJS_SRCS_FILTER:ts:}}.po+=	${_S}
 .endfor
 .endif
 .if defined(SHLIB_NAME) || \
     defined(INSTALL_PIC_ARCHIVE) && defined(LIB) && !empty(LIB)
 .for _S in ${SRCS:N*.[hly]}
-OBJS_DEPEND_GUESS.${_S:R}.pico+=	${_S}
+OBJS_DEPEND_GUESS.${_S:${OBJS_SRCS_FILTER:ts:}}.pico+=	${_S}
 .endfor
 .endif
 
Index: head/share/mk/bsd.prog.mk
===================================================================
--- head/share/mk/bsd.prog.mk
+++ head/share/mk/bsd.prog.mk
@@ -85,7 +85,7 @@
 
 .if defined(SRCS)
 
-OBJS+=  ${SRCS:N*.h:R:S/$/.o/g}
+OBJS+=  ${SRCS:N*.h:${OBJS_SRCS_FILTER:ts:}:S/$/.o/g}
 
 .if target(beforelinking)
 beforelinking: ${OBJS}