Index: kconfig/merge_config.sh
===================================================================
--- kconfig.orig/merge_config.sh
+++ kconfig/merge_config.sh
@@ -34,12 +34,16 @@ usage() {
 	echo "  -r    list redundant entries when merging fragments"
 	echo "  -O    dir to put generated output files.  Consider setting \$KCONFIG_CONFIG instead."
 	echo "  -e    colon-separated list of br2-external trees to use (optional)"
+	echo
+	echo "Used prefix: '$CONFIG_PREFIX'. You can redefine it with \$CONFIG_
+	environment variable."
 }
 
 RUNMAKE=true
 ALLTARGET=alldefconfig
 WARNREDUN=false
 OUTPUT=.
+CONFIG_PREFIX=${CONFIG_-CONFIG_}
 
 while true; do
 	case $1 in
@@ -105,7 +109,8 @@ if [ ! -r "$INITFILE" ]; then
 fi
 
 MERGE_LIST=$*
-SED_CONFIG_EXP="s/^\(# \)\{0,1\}\(CONFIG_[a-zA-Z0-9_]*\)[= ].*/\2/p"
+SED_CONFIG_EXP="s/^\(# \)\{0,1\}\(${CONFIG_PREFIX}[a-zA-Z0-9_]*\)[= ].*/\2/p"
+
 TMP_FILE=$(mktemp -t .tmp.config.XXXXXXXXXX)
 
 echo "Using $INITFILE as base"