Index: pym/portage/__init__.py
===================================================================
--- pym/portage/__init__.py	(revision 13855)
+++ pym/portage/__init__.py	(revision 13856)
@@ -1048,6 +1048,7 @@
 		"EBUILD_PHASE", "EMERGE_FROM", "HOMEPAGE", "INHERITED", "IUSE",
 		"KEYWORDS", "LICENSE", "PDEPEND", "PF", "PKGUSE",
 		"PORTAGE_CONFIGROOT", "PORTAGE_IUSE", "PORTAGE_REPO_NAME",
+		"PORTAGE_SETSID",
 		"PORTAGE_USE", "PROPERTIES", "PROVIDE", "RDEPEND", "RESTRICT",
 		"ROOT", "SLOT", "SRC_URI"
 	]
Index: bin/isolated-functions.sh
===================================================================
--- bin/isolated-functions.sh	(revision 13855)
+++ bin/isolated-functions.sh	(revision 13856)
@@ -536,7 +536,8 @@
 			PORTAGE_DEPCACHEDIR PORTAGE_GID PORTAGE_INST_GID \
 			PORTAGE_INST_UID PORTAGE_LOG_FILE PORTAGE_MASTER_PID \
 			PORTAGE_QUIET \
-			PORTAGE_REPO_NAME PORTAGE_RESTRICT PORTAGE_UPDATE_ENV \
+			PORTAGE_REPO_NAME PORTAGE_RESTRICT \
+			PORTAGE_SETSID PORTAGE_UPDATE_ENV \
 			PORTAGE_VERBOSE PORTAGE_WORKDIR_MODE PORTDIR \
 			PORTDIR_OVERLAY ${!PORTAGE_SANDBOX_*} PREROOTPATH \
 			PROFILE_PATHS PWORKDIR QA_INTERCEPTORS \
Index: bin/ebuild.sh
===================================================================
--- bin/ebuild.sh	(revision 13855)
+++ bin/ebuild.sh	(revision 13856)
@@ -71,6 +71,17 @@
 PATH=$PORTAGE_BIN_PATH/ebuild-helpers:$PREROOTPATH${PREROOTPATH:+:}/usr/local/sbin:/sbin:/usr/sbin:/usr/local/bin:/bin:/usr/bin${ROOTPATH:+:}$ROOTPATH
 export PATH
 
+if [[ -z $PORTAGE_SETSID && \
+	-n $EBUILD_SH_ARGS && $EBUILD_SH_ARGS != depend ]] ; then
+	if type -P setsid >/dev/null ; then
+		# Use setsid to create a new login session so that we can use SIGHUP
+		# to ensure that no orphaned subprocesses are left running.
+		export PORTAGE_SETSID=1
+		exec setsid "$PORTAGE_BIN_PATH/ebuild.sh" $EBUILD_SH_ARGS
+	fi
+fi
+trap '[[ $PORTAGE_SETSID = 1 ]] && { trap : SIGHUP ; kill -s SIGHUP 0 ; }' EXIT
+
 source "${PORTAGE_BIN_PATH}/isolated-functions.sh"  &>/dev/null
 
 # Set IMAGE for minimal backward compatibility with