diff --git a/Manual.md b/Manual.md
index ff6e00e0c9b..626c0faba09 100644
--- a/Manual.md
+++ b/Manual.md
@@ -827,6 +827,11 @@ package accordingly. Additionally, the following functions are available:
 
   Emits an error and exits if both options are set at the same time.
 
+- *vopt_onoff()* `vopt_onoff <option> <property>`
+
+  Outputs `-D<property>=ON` if the option is set, or
+  `-D<property>=OFF` otherwise.
+
 The following example shows how to change a source package that uses GNU
 configure to enable a new build option to support PNG images:
 
diff --git a/common/environment/setup/options.sh b/common/environment/setup/options.sh
index 72a89a2e08c..a18e4d544bf 100644
--- a/common/environment/setup/options.sh
+++ b/common/environment/setup/options.sh
@@ -28,3 +28,13 @@ vopt_conflict() {
         msg_error "options '${opt1}' and '${opt2}' conflict\n"
     fi
 }
+
+vopt_onoff() {
+    local opt="$1" prop="$2"
+    if [ "$#" -lt "2" ]; then
+        msg_error "vopt_onoff <build_option> <property>: missing values\n"
+    elif [ "$#" -gt "2" ]; then
+        msg_error "vopt_onoff $opt: $(($# - 2)) excess parameter(s)\n"
+    fi
+    vopt_if "$1" "-D${prop}=ON" "-D${prop}=OFF"
+}