diff --git a/Lib/argparse.py b/Lib/argparse.py
index 9a67b41..5820d0d 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2132,7 +2132,7 @@
                 action = self._option_string_actions[option_string]
                 return action, option_string, explicit_arg
 
-        if self.allow_abbrev:
+        if self.allow_abbrev or not arg_string.startswith('--'):
             # search through all possible prefixes of the option string
             # and all actions in the parser for possible interpretations
             option_tuples = self._get_option_tuples(arg_string)
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 9079d4b..5128dc5 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -785,6 +785,25 @@
         ('--foonly 7 --foodle --foo 2', NS(foo='2', foodle=True, foonly='7')),
     ]
 
+
+class TestDisallowLongAbbreviationAllowsShortGrouping(ParserTestCase):
+    """Do not allow abbreviations of long options at all"""
+
+    parser_signature = Sig(allow_abbrev=False)
+    argument_signatures = [
+        Sig('-r'),
+        Sig('-c', action='count'),
+    ]
+    failures = ['-r', '-c -r']
+    successes = [
+        ('', NS(r=None, c=None)),
+        ('-ra', NS(r='a', c=None)),
+        ('-rcc', NS(r='cc', c=None)),
+        ('-cc', NS(r=None, c=2)),
+        ('-cc -ra', NS(r='a', c=2)),
+        ('-ccrcc', NS(r='cc', c=2)),
+    ]
+
 # ================
 # Positional tests
 # ================