Index: share/mk/bsd.links.mk
===================================================================
--- share/mk/bsd.links.mk
+++ share/mk/bsd.links.mk
@@ -13,10 +13,27 @@
 
 afterinstall: _installlinks
 .ORDER: realinstall _installlinks
+# If the source and destination file are the same file (e.g. Mail/mail on a
+# case-insensitive file-system) we have to pass -S to install(1) to avoid
+# deleting the source file.
 _installlinks:
 .for s t in ${LINKS}
+.if ${s:tl} == ${t:tl}
+	if test "${DESTDIR}${t}" -ef "${DESTDIR}${s}"; then \
+		echo "Note: requested hard link from ${t} to ${s} on case-insensitive file system."; \
+	fi
+	${INSTALL_LINK} -S ${TAG_ARGS} ${DESTDIR}${s} ${DESTDIR}${t}
+.else
 	${INSTALL_LINK} ${TAG_ARGS} ${DESTDIR}${s} ${DESTDIR}${t}
+.endif
 .endfor
 .for s t in ${SYMLINKS}
+.if ${s:tl} == ${t:tl}
+	if test "${DESTDIR}${t}" -ef "${DESTDIR}${s}"; then \
+		echo "Note: requested symlink from ${t} to ${s} on case-insensitive file system."; \
+	fi
+	${INSTALL_SYMLINK} -S ${TAG_ARGS} ${s} ${DESTDIR}${t}
+.else
 	${INSTALL_SYMLINK} ${TAG_ARGS} ${s} ${DESTDIR}${t}
+.endif
 .endfor
Index: share/mk/bsd.man.mk
===================================================================
--- share/mk/bsd.man.mk
+++ share/mk/bsd.man.mk
@@ -226,8 +226,20 @@
 .endif	# ${MK_MANCOMPRESS} == "no"
 .endif
 .for l t in ${_MANLINKS}
+.if ${l:tl} == ${t:tl}
+	# If the source and destination file are the same file (e.g. Mail/mail
+	# on a case-insensitive file-system) we have to pass -S to install to avoid
+	# deleting the source file.
+	if test "${DESTDIR}${l}${ZEXT}" -ef "${DESTDIR}${t}${ZEXT}"; then \
+		echo "Note: requested man link from ${t} to ${s} on case-insensitive file system."; \
+	else \
+		rm -f ${DESTDIR}${t} ${DESTDIR}${t}${MCOMPRESS_EXT}; \
+	fi
+	${INSTALL_MANLINK} -S ${TAG_ARGS} ${DESTDIR}${l}${ZEXT} ${DESTDIR}${t}${ZEXT}
+.else
 	rm -f ${DESTDIR}${t} ${DESTDIR}${t}${MCOMPRESS_EXT}; \
 	    ${INSTALL_MANLINK} ${TAG_ARGS} ${DESTDIR}${l}${ZEXT} ${DESTDIR}${t}${ZEXT}
+.endif
 .endfor
 
 manlint: