diff --git a/dev-db/mongodb/Manifest b/dev-db/mongodb/Manifest
index e0116fc39862e..6c786db69ba3d 100644
--- a/dev-db/mongodb/Manifest
+++ b/dev-db/mongodb/Manifest
@@ -5,3 +5,4 @@ DIST mongodb-src-r4.0.16.tar.gz 50091501 BLAKE2B a383f9fef8e5b2ceda9646dfc4f4f46
 DIST mongodb-src-r4.0.19.tar.gz 50126414 BLAKE2B 2691e2a9c8833ff9a086b28fd137bc8e8f10d58570117657c7cc01edbf61568ae62f58440d72e8711de98b9fc6868c1095b4ee88eb7b0eb63ea45ce19e842edd SHA512 57032a009ea7e79de4cac496a2d1266b83b99cc45eb9f1169be2fcdca1ed2003a659ceedf9eafbd4aa7fc5b3b0513066a5d712af7666cee5a897b2a2d7dd30cb
 DIST mongodb-src-r4.2.3.tar.gz 61565615 BLAKE2B 695310a497e57f1c735f175f5b321c93cda376ec734bb08d4cabbd562a865b327f529560220be9c22f571cc70af333a77f0116f04c7f7e3a40f275ab53ab1bf9 SHA512 60e9091cfab4a189a937dfa7ce232eb6ead2ca192c916579f4fb5da2040aa340ae9de0ea8c7a4ccb0edcfdbdf6e666144657f171c3f23c0a62bccf27cd351c69
 DIST mongodb-src-r4.2.6.tar.gz 61671088 BLAKE2B 7f2b6240b05639d2bbe37ea148cbb225b30813879f71a5fc3c135ef7debd58edf75abe925d00f9ff96dc6a75a525b4504e25254b0046326069c05bb1dfd60827 SHA512 117c910807a8363aab6b899b436a4b06564b6e53abfa7f0fe6e01c1e242401ab5a3634d9edc5e0a5e2d548a480c90b70ac492eb199b3f2476d9045a78e376af8
+DIST mongodb-src-r4.2.8.tar.gz 61730247 BLAKE2B f1d98b8ac8f62c0c7aff100ef663bb20345de0e77e0ff420817db0843fe735b58af8075578a7f8d83cc9dc4e597c95ae09f89ce7a21cf8146ff15bcb11eba924 SHA512 163fce480762bd377d6c78b661bfe51fc883223a5309a68f9556e1bafb99e26e476d81dbe6de825d90469e835442be097be630ca9678e54b9d09091e0b5d67c4
diff --git a/dev-db/mongodb/mongodb-4.2.8.ebuild b/dev-db/mongodb/mongodb-4.2.8.ebuild
new file mode 100644
index 0000000000000..b88bcf9c846f5
--- /dev/null
+++ b/dev-db/mongodb/mongodb-4.2.8.ebuild
@@ -0,0 +1,174 @@
+# Copyright 1999-2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+PYTHON_COMPAT=( python3_{6,7} )
+
+SCONS_MIN_VERSION="2.5.0"
+CHECKREQS_DISK_BUILD="2400M"
+CHECKREQS_DISK_USR="512M"
+CHECKREQS_MEMORY="1024M"
+
+inherit check-reqs flag-o-matic multiprocessing pax-utils python-any-r1 scons-utils systemd toolchain-funcs
+
+MY_P=${PN}-src-r${PV/_rc/-rc}
+
+DESCRIPTION="A high-performance, open source, schema-free document-oriented database"
+HOMEPAGE="https://www.mongodb.com"
+SRC_URI="https://fastdl.mongodb.org/src/${MY_P}.tar.gz"
+
+LICENSE="Apache-2.0 SSPL-1"
+SLOT="0"
+KEYWORDS="~amd64 ~arm64"
+IUSE="debug kerberos libressl lto ssl test +tools"
+RESTRICT="!test? ( test )"
+
+RDEPEND="acct-group/mongodb
+	acct-user/mongodb
+	>=app-arch/snappy-1.1.3
+	>=dev-cpp/yaml-cpp-0.6.2:=
+	>=dev-libs/boost-1.70:=[threads(+)]
+	>=dev-libs/libpcre-8.42[cxx]
+	app-arch/zstd
+	dev-libs/snowball-stemmer
+	net-libs/libpcap
+	>=sys-libs/zlib-1.2.11:=
+	kerberos? ( dev-libs/cyrus-sasl[kerberos] )
+	ssl? (
+		!libressl? ( >=dev-libs/openssl-1.0.1g:0= )
+		libressl? ( dev-libs/libressl:0= )
+	)"
+DEPEND="${RDEPEND}
+	${PYTHON_DEPS}
+	$(python_gen_any_dep '
+		test? ( dev-python/pymongo[${PYTHON_USEDEP}] dev-python/requests[${PYTHON_USEDEP}] )
+		>=dev-util/scons-2.5.0[${PYTHON_USEDEP}]
+		dev-python/cheetah3[${PYTHON_USEDEP}]
+		dev-python/psutil[${PYTHON_USEDEP}]
+		dev-python/pyyaml[${PYTHON_USEDEP}]
+	')
+	sys-libs/ncurses:0=
+	sys-libs/readline:0=
+	debug? ( dev-util/valgrind )"
+PDEPEND="tools? ( >=app-admin/mongo-tools-${PV} )"
+
+PATCHES=(
+	"${FILESDIR}/${PN}-4.2.0-fix-scons.patch"
+	"${FILESDIR}/${PN}-4.0.0-no-compass.patch"
+)
+
+S="${WORKDIR}/${MY_P}"
+
+python_check_deps() {
+	if use test; then
+		has_version "dev-python/pymongo[${PYTHON_USEDEP}]" || return 1
+		has_version "dev-python/requests[${PYTHON_USEDEP}]" || return 1
+	fi
+
+	has_version ">=dev-util/scons-2.5.0[${PYTHON_USEDEP}]" &&
+	has_version "dev-python/cheetah3[${PYTHON_USEDEP}]" &&
+	has_version "dev-python/psutil[${PYTHON_USEDEP}]" &&
+	has_version "dev-python/pyyaml[${PYTHON_USEDEP}]"
+}
+
+pkg_pretend() {
+	if [[ -n ${REPLACING_VERSIONS} ]]; then
+		if ver_test "$REPLACING_VERSIONS" -lt 4.0; then
+			ewarn "To upgrade from a version earlier than the 4.0-series, you must"
+			ewarn "successively upgrade major releases until you have upgraded"
+			ewarn "to 4.0-series. Then upgrade to 4.2 series."
+		else
+			ewarn "Be sure to set featureCompatibilityVersion to 4.0 before upgrading."
+		fi
+	fi
+}
+
+src_prepare() {
+	default
+
+	# remove bundled libs
+	rm -r src/third_party/{boost-*,pcre-*,scons-*,snappy-*,yaml-cpp-*,zlib-*,zstandard-*} || die
+
+	# remove compass
+	rm -r src/mongo/installer/compass || die
+}
+
+src_configure() {
+	# https://github.com/mongodb/mongo/wiki/Build-Mongodb-From-Source
+	# --use-system-icu fails tests
+	# --use-system-tcmalloc is strongly NOT recommended:
+	scons_opts=(
+		CC="$(tc-getCC)"
+		CXX="$(tc-getCXX)"
+
+		--disable-warnings-as-errors
+		--use-system-boost
+		--use-system-pcre
+		--use-system-snappy
+		--use-system-stemmer
+		--use-system-yaml
+		--use-system-zlib
+		--use-system-zstd
+	)
+
+	use arm64 && scons_opts+=( --use-hardware-crc32=off ) # Bug 701300
+	use debug && scons_opts+=( --dbg=on )
+	use kerberos && scons_opts+=( --use-sasl-client )
+	use lto && scons_opts+=( --lto=on )
+	use ssl && scons_opts+=( --ssl )
+
+	# respect mongoDB upstream's basic recommendations
+	# see bug #536688 and #526114
+	if ! use debug; then
+		filter-flags '-m*'
+		filter-flags '-O?'
+	fi
+
+	default
+}
+
+src_compile() {
+	escons "${scons_opts[@]}" core tools
+}
+
+# FEATURES="test -usersandbox" emerge dev-db/mongodb
+src_test() {
+	"${EPYTHON}" ./buildscripts/resmoke.py --dbpathPrefix=test --suites core --jobs=$(makeopts_jobs) || die "Tests failed"
+}
+
+src_install() {
+	escons "${scons_opts[@]}" --nostrip install --prefix="${ED}"/usr
+
+	doman debian/mongo*.1
+	dodoc README docs/building.md
+
+	newinitd "${FILESDIR}/${PN}.initd-r3" ${PN}
+	newconfd "${FILESDIR}/${PN}.confd-r3" ${PN}
+	newinitd "${FILESDIR}/mongos.initd-r3" mongos
+	newconfd "${FILESDIR}/mongos.confd-r3" mongos
+
+	insinto /etc
+	newins "${FILESDIR}/${PN}.conf-r3" ${PN}.conf
+	newins "${FILESDIR}/mongos.conf-r2" mongos.conf
+
+	systemd_dounit "${FILESDIR}/${PN}.service"
+
+	insinto /etc/logrotate.d/
+	newins "${FILESDIR}/${PN}.logrotate" ${PN}
+
+	# see bug #526114
+	pax-mark emr "${ED}"/usr/bin/{mongo,mongod,mongos}
+
+	local x
+	for x in /var/{lib,log}/${PN}; do
+		diropts -m0750 -o mongodb -g mongodb
+		keepdir "${x}"
+	done
+}
+
+pkg_postinst() {
+	ewarn "Make sure to read the release notes and follow the upgrade process:"
+	ewarn "  https://docs.mongodb.com/manual/release-notes/$(ver_cut 1-2)/"
+	ewarn "  https://docs.mongodb.com/manual/release-notes/$(ver_cut 1-2)/#upgrade-procedures"
+}