--- a/tools/update-packaging/make_incremental_update.sh
+++ b/tools/update-packaging/make_incremental_update.sh
@@ -177,18 +177,43 @@ for ((i=0; $i<$num_oldfiles; i=$i+1)); d
     fi
 
     if ! diff "$olddir/$f" "$newdir/$f" > /dev/null; then
       # Compute both the compressed binary diff and the compressed file, and
       # compare the sizes.  Then choose the smaller of the two to package.
       dir=$(dirname "$workdir/$f")
       mkdir -p "$dir"
       notice "diffing \"$f\""
-      $MBSDIFF "$olddir/$f" "$newdir/$f" "$workdir/$f.patch"
-      $BZIP2 -z9 "$workdir/$f.patch"
+      # MBSDIFF_HOOK represents the communication interface with funsize and,
+      # if enabled, caches the intermediate patches for future use and
+      # compute avoidance
+      #
+      # An example of MBSDIFF_HOOK env variable could look like this:
+      # export MBSDIFF_HOOK="myscript.sh -A https://funsize/api -c /home/user"
+      # where myscript.sh has the following usage:
+      # myscript.sh -A SERVER-URL [-c LOCAL-CACHE-DIR-PATH] [-g] [-u] \
+      #   PATH-FROM-URL PATH-TO-URL PATH-PATCH SERVER-URL
+      #
+      # Note: patches are bzipped stashed in funsize to gain more speed
+
+      # if service is not enabled then default to old behavior
+      if [ -z "$MBSDIFF_HOOK" ]; then
+        $MBSDIFF "$olddir/$f" "$newdir/$f" "$workdir/$f.patch"
+        $BZIP2 -z9 "$workdir/$f.patch"
+      else
+        # if service enabled then check patch existence for retrieval
+        if $MBSDIFF_HOOK -g "$olddir/$f" "$newdir/$f" "$workdir/$f.patch.bz2"; then
+          notice "file \"$f\" found in funsize, diffing skipped"
+        else
+          # if not found already - compute it and cache it for future use
+          $MBSDIFF "$olddir/$f" "$newdir/$f" "$workdir/$f.patch"
+          $BZIP2 -z9 "$workdir/$f.patch"
+          $MBSDIFF_HOOK -u "$olddir/$f" "$newdir/$f" "$workdir/$f.patch.bz2"
+        fi
+      fi
       $BZIP2 -cz9 "$newdir/$f" > "$workdir/$f"
       copy_perm "$newdir/$f" "$workdir/$f"
       patchfile="$workdir/$f.patch.bz2"
       patchsize=$(get_file_size "$patchfile")
       fullsize=$(get_file_size "$workdir/$f")
 
       if [ $patchsize -lt $fullsize ]; then
         make_patch_instruction "$f" "$updatemanifestv2" "$updatemanifestv3"