diff --git a/debian/changelog b/debian/changelog
index eedb5b96..cc0d8c57 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+livecd-rootfs (2.408.31) xenial; urgency=medium
+
+  * Backport snap preseeding functions from bionic. (LP: #1771177)
+
+ -- Mathieu Trudel-Lapierre <cyphermox@ubuntu.com>  Mon, 14 May 2018 14:16:35 -0400
+
 livecd-rootfs (2.408.30) xenial; urgency=medium
 
   * Set the default locale to C.UTF-8 in minimized cloud images.
diff --git a/live-build/auto/config b/live-build/auto/config
index badff46a..3c659bef 100755
--- a/live-build/auto/config
+++ b/live-build/auto/config
@@ -34,6 +34,7 @@ if [ -z "$MIRROR" ]; then
 fi
 
 mkdir -p config/package-lists
+cp -af /usr/share/livecd-rootfs/live-build/functions config/functions
 
 add_task ()
 {
@@ -685,9 +686,11 @@ lb config noauto \
 
 echo "LB_CHROOT_HOOKS=\"$CHROOT_HOOKS\"" >> config/chroot
 echo "SUBPROJECT=\"${SUBPROJECT:-}\"" >> config/chroot
+echo "LB_DISTRIBUTION=\"$SUITE\"" >> config/chroot
 echo "LB_BINARY_HOOKS=\"$BINARY_HOOKS\"" >> config/binary
 echo "BUILDSTAMP=\"$NOW\"" >> config/binary
 echo "SUBPROJECT=\"${SUBPROJECT:-}\"" >> config/binary
+echo "LB_DISTRIBUTION=\"$SUITE\"" >> config/binary
 
 case $ARCH+$SUBARCH in
 	armhf+raspi2)
diff --git a/live-build/functions b/live-build/functions
new file mode 100644
index 00000000..4772c28b
--- /dev/null
+++ b/live-build/functions
@@ -0,0 +1,126 @@
+# vi: ts=4 expandtab syntax=sh
+
+#imagesize=${IMAGE_SIZE:-$((2252*1024**2))}  # 2.2G (the current size we ship)
+imagesize=${IMAGE_SIZE:-2361393152}  # 2.2G (the current size we ship)
+
+release_ver() {
+    # Return the release version number
+    distro-info --series="$LB_DISTRIBUTION" -r | awk '{ print $1 }'
+}
+
+_snap_preseed() {
+    # Download the snap/assertion and add to the preseed
+    local CHROOT_ROOT=$1
+    local SNAP=$2
+    local SNAP_NAME=${SNAP%/*}
+    local CHANNEL=${3:?Snap channel must be specified}
+
+    local seed_dir="$CHROOT_ROOT/var/lib/snapd/seed"
+    local snaps_dir="$seed_dir/snaps"
+    local seed_yaml="$seed_dir/seed.yaml"
+    local assertions_dir="$seed_dir/assertions"
+
+    # Download the snap & assertion
+    local snap_download_failed=0
+    chroot $CHROOT_ROOT sh -c "
+        set -x;
+        cd /var/lib/snapd/seed;
+        SNAPPY_STORE_NO_CDN=1 snap download \
+            --channel=$CHANNEL \"$SNAP_NAME\"" || snap_download_failed=1
+    if [ $snap_download_failed = 1 ] ; then
+        echo "If the channel ($CHANNEL) includes '*/ubuntu-##.##' track per "
+        echo "Ubuntu policy (ex. stable/ubuntu-18.04) the publisher will need "
+        echo "to temporarily create the channel/track to allow fallback during"
+        echo "download (ex. stable/ubuntu-18.04 falls back to stable if the"
+        echo "prior had been created in the past)."
+        exit 1
+    fi
+
+    mv -v $seed_dir/*.assert $assertions_dir
+    mv -v $seed_dir/*.snap $snaps_dir
+
+    # Add the snap to the seed.yaml
+    ! [ -e $seed_yaml ] && echo "snaps:" > $seed_yaml
+    cat <<EOF >> $seed_yaml
+  -
+    name: ${SNAP_NAME}
+    channel: ${CHANNEL}
+EOF
+
+    case ${SNAP} in */classic) echo "    classic: true" >> $seed_yaml;; esac
+
+    echo -n "    file: " >> $seed_yaml
+    (cd $snaps_dir; ls -1 ${SNAP_NAME}_*.snap) >> $seed_yaml
+}
+
+snap_prepare_assertions() {
+    # Configure basic snapd assertions
+    local CHROOT_ROOT=$1
+    # A colon-separated string of brand:model to be used for the image's model
+    # assertion
+    local CUSTOM_BRAND_MODEL=$2
+
+    local seed_dir="$CHROOT_ROOT/var/lib/snapd/seed"
+    local snaps_dir="$seed_dir/snaps"
+    local assertions_dir="$seed_dir/assertions"
+    local model_assertion="$assertions_dir/model"
+    local account_key_assertion="$assertions_dir/account-key"
+    local account_assertion="$assertions_dir/account"
+
+    mkdir -p "$assertions_dir"
+    mkdir -p "$snaps_dir"
+
+    local brand="$(echo $CUSTOM_BRAND_MODEL | cut -d: -f 1)"
+    local model="$(echo $CUSTOM_BRAND_MODEL | cut -d: -f 2)"
+
+    if ! [ -e "$model_assertion" ] ; then
+        snap known --remote model series=16 \
+            model=$model brand-id=$brand \
+            > "$model_assertion"
+    fi
+
+    if ! [ -e "$account_key_assertion" ] ; then
+        local account_key=$(sed -n -e's/sign-key-sha3-384: //p' \
+            < "$model_assertion")
+        snap known --remote account-key \
+            public-key-sha3-384="$account_key" \
+            > "$account_key_assertion"
+    fi
+
+
+    if ! [ -e "$account_assertion" ] ; then
+        local account=$(sed -n -e's/account-id: //p' < "$account_key_assertion")
+        snap known --remote account account-id=$account \
+            > "$account_assertion"
+    fi
+}
+
+snap_prepare() {
+    # Configure basic snapd assertions and pre-seeds the 'core' snap
+    local CHROOT_ROOT=$1
+    # Optional. If set, should be a colon-separated string of brand:model to be
+    # used for the image's model assertion
+    local CUSTOM_BRAND_MODEL=${2:-generic:generic-classic}
+
+    local seed_dir="$CHROOT_ROOT/var/lib/snapd/seed"
+    local snaps_dir="$seed_dir/snaps"
+
+    snap_prepare_assertions "$CHROOT_ROOT" "$CUSTOM_BRAND_MODEL"
+
+    # Download the core snap
+    if ! [ -f $snaps_dir/core_[0-9]*.snap ] ; then
+        _snap_preseed $CHROOT_ROOT core stable
+    fi
+}
+
+snap_preseed() {
+    # Preseed a snap in the image
+    local CHROOT_ROOT=$1
+    local SNAP=$2
+    # Per Ubuntu policy, all seeded snaps (with the exception of the core
+    # snap) must pull from stable/ubuntu-$(release_ver) as their channel.
+    local CHANNEL=${3:-"stable/ubuntu-$(release_ver)"}
+
+    snap_prepare $CHROOT_ROOT
+    _snap_preseed $CHROOT_ROOT $SNAP $CHANNEL
+}