diff --git a/Lib/argparse.py b/Lib/argparse.py
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1894,6 +1894,13 @@
             selected_pattern = arg_strings_pattern[start_index:]
             arg_counts = match_partial(positionals, selected_pattern)
 
+            # if we haven't hit the end of the command line strings,
+            # then don't consume any final zero-width arguments yet
+            # (we may need to parse some more optionals first)
+            if start_index + sum(arg_counts) != len(arg_strings_pattern):
+                while arg_counts and arg_counts[-1] == 0:
+                    arg_counts.pop()
+
             # slice off the appropriate arg strings for each Positional
             # and add the Positional and its args to the list
             for action, arg_count in zip(positionals, arg_counts):
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1254,6 +1254,56 @@
     ]
 
 
+class TestNargsOneOrMoreDeferred(ParserTestCase):
+    """Tests specifying a positional with nargs='*' that must be deferred"""
+
+    argument_signatures = [
+        Sig('-x', action='store_true'),
+        Sig('y'),
+        Sig('z', nargs='*'),
+    ]
+    failures = ['', '-x']
+    successes = [
+        ('Y', NS(x=False, y='Y', z=[])),
+        ('Y -x', NS(x=True, y='Y', z=[])),
+        ('Y -x Z Z', NS(x=True, y='Y', z=['Z', 'Z'])),
+    ]
+
+
+class TestNargsZeroOrOneDeferred(ParserTestCase):
+    """Tests specifying a positional with nargs='?' that must be deferred"""
+
+    argument_signatures = [
+        Sig('-x', action='store_true'),
+        Sig('y'),
+        Sig('z', nargs='?'),
+    ]
+    failures = ['', '-x']
+    successes = [
+        ('Y', NS(x=False, y='Y', z=None)),
+        ('Y -x', NS(x=True, y='Y', z=None)),
+        ('Y -x Z', NS(x=True, y='Y', z='Z')),
+    ]
+
+
+class TestNargsMultipleDeferred(ParserTestCase):
+    """Tests specifying a positional multiple nargs that must be deferred"""
+
+    argument_signatures = [
+        Sig('-w', action='store_true'),
+        Sig('x'),
+        Sig('y', nargs='?'),
+        Sig('z', nargs='*'),
+    ]
+    failures = ['', '-x']
+    successes = [
+        ('X', NS(w=False, x='X', y=None, z=[])),
+        ('X -w', NS(w=True, x='X', y=None, z=[])),
+        ('X -w Y', NS(w=True, x='X', y='Y', z=[])),
+        ('X -w Y Z', NS(w=True, x='X', y='Y', z=['Z'])),
+    ]
+
+
 class TestOptionLike(ParserTestCase):
     """Tests options that may or may not be arguments"""