diff --git a/litex/build/parser.py b/litex/build/parser.py
index 5e74460ec..87ef6bf4f 100644
--- a/litex/build/parser.py
+++ b/litex/build/parser.py
@@ -32,6 +32,9 @@ class LiteXArgumentParser(argparse.ArgumentParser):
         toolchain used at build time
     _default_toolchain: str
         toolchain to use by default or when no selection is done  by the user
+    _args_default: dict
+        couple argument name / default value to apply just before to call
+        parse_args()
     """
     def __init__(self, platform=None, **kwargs):
         """
@@ -55,6 +58,7 @@ class LiteXArgumentParser(argparse.ArgumentParser):
         self._toolchain         = None
         self._target_group      = None
         self._logging_group     = None
+        self._args_default      = {}
         if platform is not None:
             self.set_platform(platform)
             self.add_target_group()
@@ -111,6 +115,18 @@ class LiteXArgumentParser(argparse.ArgumentParser):
         self._logging_group.add_argument("--log-filename", default=None,   help="Logging filename.")
         self._logging_group.add_argument("--log-level",    default="info", help="Logging level: debug, info (default), warning error or critical.")
 
+    def set_defaults(self, **kwargs):
+        """
+        Overrides argparse.ArgumentParser.set_defaults. Used to delay default
+        values application
+
+        Parameters
+        ==========
+        kwargs: dict
+            couple argument name / default value
+        """
+        self._args_default.update(kwargs)
+
     @property
     def builder_argdict(self):
         """
@@ -178,6 +194,10 @@ class LiteXArgumentParser(argparse.ArgumentParser):
         if cpu_cls is not None and hasattr(cpu_cls, "args_fill"):
             cpu_cls.args_fill(self)
 
+        # Injects arguments default values
+        if len(self._args_default):
+            argparse.ArgumentParser.set_defaults(self, **self._args_default)
+
         # Parse args.
         self._args = argparse.ArgumentParser.parse_args(self, args, namespace)