diff --git a/Makefile b/Makefile
index 1cf15cefd1..fffc188f9a 100644
--- a/Makefile
+++ b/Makefile
@@ -740,7 +740,8 @@ DO_STATIC_RELA =
 endif
 
 # Always append ALL so that arch config.mk's can add custom ones
-ALL-y += u-boot.srec u-boot.bin u-boot.sym System.map u-boot.cfg binary_size_check
+ALL-y += u-boot.srec u-boot.bin u-boot.sym System.map u-boot.cfg \
+	binary_size_check no_new_adhoc_configs_check
 
 ALL-$(CONFIG_ONENAND_U_BOOT) += u-boot-onenand.bin
 ifeq ($(CONFIG_SPL_FSL_PBL),y)
@@ -938,6 +939,13 @@ u-boot.dis:	u-boot
 u-boot.cfg:	include/config.h FORCE
 	$(call if_changed,cpp_cfg)
 
+# Check that this build does not use CONFIG options that we don't know about
+# unless they are in Kconfig. All the existing CONFIG options are whitelisted,
+# so new ones should not be added.
+no_new_adhoc_configs_check: u-boot.cfg FORCE
+	$(srctree)/scripts/check-config.sh $< \
+		$(srctree)/scripts/config_whitelist.txt ${srctree} 1>&2
+
 ifdef CONFIG_TPL
 SPL_PAYLOAD := tpl/u-boot-with-tpl.bin
 else
diff --git a/scripts/check-config.sh b/scripts/check-config.sh
new file mode 100755
index 0000000000..28c8fe98ba
--- /dev/null
+++ b/scripts/check-config.sh
@@ -0,0 +1,55 @@
+#!/bin/sh
+# Copyright (c) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# Check that the u-boot.cfg file provided does not introduce any new
+# ad-hoc CONFIG options
+#
+# You can generate the list of current ad-hoc CONFIG options (those which are
+# not in Kconfig) with this command:
+#
+# export LC_ALL=C LC_COLLATE=C
+# git grep CONFIG_ |tr ' \t' '\n\n' |sed -n 's/^\(CONFIG_[A-Z0-9_]*\).*/\1/p' \
+#	|sort |uniq >scripts/config_whitelist.txt;
+# unset LC_ALL LC_COLLATE
+
+# Usage
+#    check-config.sh <path to u-boot.cfg> <path to whitelist file> <source dir>
+#
+# For example:
+#   scripts/check-config.sh b/chromebook_link/u-boot.cfg kconfig_whitelist.txt .
+
+path="$1"
+whitelist="$2"
+srctree="$3"
+
+# Temporary files
+configs="${path}.configs"
+suspects="${path}.suspects"
+ok="${path}.ok"
+new_adhoc="${path}.adhoc"
+
+export LC_ALL=C
+export LC_COLLATE=C
+
+cat ${path} |sed -n 's/^#define \(CONFIG_[A-Za-z0-9_]*\).*/\1/p' |sort |uniq \
+	>${configs}
+
+comm -23 ${configs} ${whitelist} > ${suspects}
+
+cat `find ${srctree} -name "Kconfig*"` |sed -n \
+	-e 's/^config *\([A-Za-z0-9_]*\).*$/CONFIG_\1/p' \
+	-e 's/^menuconfig \([A-Za-z0-9_]*\).*$/CONFIG_\1/p' |sort |uniq > ${ok}
+comm -23 ${suspects} ${ok} >${new_adhoc}
+if [ -s ${new_adhoc} ]; then
+	echo "Error: You must add new CONFIG options using Kconfig"
+	echo "The following new ad-hoc CONFIG options were detected:"
+	cat ${new_adhoc}
+	echo
+	echo "Please add these via Kconfig instead. Find a suitable Kconfig"
+	echo "file and add a 'config' or 'menuconfig' option."
+	# Don't delete the temporary files in case they are useful
+	exit 1
+else
+	rm ${suspects} ${ok} ${new_adhoc}
+fi