diff --git a/eclass/qt5-build.eclass b/eclass/qt5-build.eclass
index 279ece28e1d..eb7cfdec977 100644
--- a/eclass/qt5-build.eclass
+++ b/eclass/qt5-build.eclass
@@ -198,21 +198,7 @@ qt5-build_src_prepare() {
 		sed -i -e "/Creating qmake/i if [ '!' -e \"\$outpath/bin/qmake\" ]; then" \
 			-e '/echo "Done."/a fi' configure || die "sed failed (skip qmake bootstrap)"
 
-		# Respect CC, CXX, *FLAGS, MAKEOPTS and EXTRA_EMAKE when bootstrapping qmake
-		sed -i -e "/outpath\/qmake\".*\"\$MAKE\")/ s|)| \
-			${MAKEOPTS} ${EXTRA_EMAKE} 'CC=$(tc-getCC)' 'CXX=$(tc-getCXX)' \
-			'QMAKE_CFLAGS=${CFLAGS}' 'QMAKE_CXXFLAGS=${CXXFLAGS}' 'QMAKE_LFLAGS=${LDFLAGS}'&|" \
-			-e 's/\(setBootstrapVariable\s\+\|EXTRA_C\(XX\)\?FLAGS=.*\)QMAKE_C\(XX\)\?FLAGS_\(DEBUG\|RELEASE\).*/:/' \
-			configure || die "sed failed (respect env for qmake build)"
-		sed -i -e '/^CPPFLAGS\s*=/ s/-g //' \
-			qmake/Makefile.unix || die "sed failed (CPPFLAGS for qmake build)"
-
-		# Respect CXX in bsymbolic_functions, fvisibility, precomp, and a few other tests
-		sed -i -e "/^QMAKE_CONF_COMPILER=/ s:=.*:=\"$(tc-getCXX)\":" \
-			configure || die "sed failed (QMAKE_CONF_COMPILER)"
-
-		# Respect build variables in configure tests (bug #639494)
-		sed -i -e "s|\"\$outpath/bin/qmake\" \"\$relpathMangled\" -- \"\$@\"|& $(qt5_qmake_args) |" configure || die
+		sed -i -e 's/EXTRA_CXXFLAGS/CONFIG_CXXFLAGS/' -e 's/EXTRA_LFLAGS/CONFIG_LFLAGS/' configure || die
 	fi
 
 	[[ -n ${QT5_KDEPATCHSET_REV} ]] && eapply "${WORKDIR}/${QT5_MODULE}-${PV}-gentoo-kde-${QT5_KDEPATCHSET_REV}"
@@ -240,6 +226,11 @@ qt5-build_src_configure() {
 # Runs emake in the target directories.
 qt5-build_src_compile() {
 	qt5_foreach_target_subdir emake
+	if [[ ${PN} == qtcore ]]; then
+		pushd "${QT5_BUILD_DIR}" >/dev/null || die
+		emake sub-qmake-qmake-aux-pro
+		popd >/dev/null || die
+	fi
 }
 
 # @FUNCTION: qt5-build_src_test
@@ -530,6 +521,8 @@ qt5_base_configure() {
 	# setup toolchain variables used by configure
 	tc-export AR CC CXX OBJDUMP RANLIB STRIP
 	export LD="$(tc-getCXX)"
+	export EXTRA_CXXFLAGS="${CXXFLAGS}"
+	export EXTRA_LFLAGS="${LDFLAGS}"
 
 	# bug 633838
 	unset QMAKESPEC XQMAKESPEC QMAKEPATH QMAKEFEATURES
@@ -687,6 +680,8 @@ qt5_base_configure() {
 		"${myconf[@]}"
 	)
 
+	eval "conf+=($(qt5_qmake_args))"
+
 	pushd "${QT5_BUILD_DIR}" >/dev/null || die
 
 	einfo "Configuring with: ${conf[@]}"