diff --git a/nixos/lib/make-options-doc/default.nix b/nixos/lib/make-options-doc/default.nix
index dde3cac1c1ba..e097aa5eebd8 100644
--- a/nixos/lib/make-options-doc/default.nix
+++ b/nixos/lib/make-options-doc/default.nix
@@ -40,6 +40,8 @@
 # `false`, and a different renderer may be used with different bugs and performance
 # characteristics but (hopefully) indistinguishable output.
 , allowDocBook ? true
+# whether lib.mdDoc is required for descriptions to be read as markdown.
+, markdownByDefault ? false
 }:
 
 let
@@ -152,6 +154,7 @@ in rec {
       python ${./mergeJSON.py} \
         ${lib.optionalString warningsAreErrors "--warnings-are-errors"} \
         ${lib.optionalString (! allowDocBook) "--error-on-docbook"} \
+        ${lib.optionalString markdownByDefault "--markdown-by-default"} \
         $baseJSON $options \
         > $dst/options.json
 
diff --git a/nixos/lib/make-options-doc/mergeJSON.py b/nixos/lib/make-options-doc/mergeJSON.py
index 8a8498746bf6..f8353a794b6a 100644
--- a/nixos/lib/make-options-doc/mergeJSON.py
+++ b/nixos/lib/make-options-doc/mergeJSON.py
@@ -203,6 +203,9 @@ def convertMD(options: Dict[str, Any]) -> str:
     for (name, option) in options.items():
         if optionIs(option, 'description', 'mdDoc'):
             option['description'] = convertString(name, option['description']['text'])
+        elif markdownByDefault:
+            option['description'] = convertString(name, option['description'])
+
         if optionIs(option, 'example', 'literalMD'):
             docbook = convertString(name, option['example']['text'])
             option['example'] = { '_type': 'literalDocBook', 'text': docbook }
@@ -214,6 +217,7 @@ def convertMD(options: Dict[str, Any]) -> str:
 
 warningsAreErrors = False
 errorOnDocbook = False
+markdownByDefault = False
 optOffset = 0
 for arg in sys.argv[1:]:
     if arg == "--warnings-are-errors":
@@ -222,6 +226,9 @@ for arg in sys.argv[1:]:
     if arg == "--error-on-docbook":
         optOffset += 1
         errorOnDocbook = True
+    if arg == "--markdown-by-default":
+        optOffset += 1
+        markdownByDefault = True
 
 options = pivot(json.load(open(sys.argv[1 + optOffset], 'r')))
 overrides = pivot(json.load(open(sys.argv[2 + optOffset], 'r')))