diff --git a/sphinx/domains/std.py b/sphinx/domains/std.py
index 6218de6abe..ad9ef71d17 100644
--- a/sphinx/domains/std.py
+++ b/sphinx/domains/std.py
@@ -35,7 +35,7 @@
     Final = Any
 
 # RE for option descriptions
-option_desc_re = re.compile(r'((?:/|--|-|\+)?[^\s=]+)(=?\s*.*)')
+option_desc_re = re.compile(r'((?:/|--|-|\+)?[^\s={]+)(=?\s*.*)')
 # RE for grammar tokens
 token_re = re.compile(r'`((~?\w*:)?\w+)`', re.U)
 
@@ -177,6 +177,8 @@ def handle_signature(self, sig: str, signode: desc_signature) -> str:
                                location=signode)
                 continue
             optname, args = m.groups()
+            # replace '#' with '=' in option name
+            optname = optname.replace('#', '=')
             if optname[-1] == '[' and args[-1] == ']':
                 # optional value surrounded by brackets (ex. foo[=bar])
                 optname = optname[:-1]
@@ -199,7 +201,7 @@ def handle_signature(self, sig: str, signode: desc_signature) -> str:
                     elif args[0] == ' ':
                         signode += addnodes.desc_sig_space()
                         args = args.strip()
-                    elif args[0] == '=':
+                    elif args[0] in ('=', '#'):
                         signode += addnodes.desc_sig_punctuation('=', '=')
                         args = args[1:]
                     for part in samp_role.parse(args):
@@ -940,7 +942,15 @@ def _resolve_option_xref(self, env: "BuildEnvironment", fromdocname: str,
                              node: pending_xref, contnode: Element) -> Optional[Element]:
         progname = node.get('std:program')
         target = target.strip()
-        docname, labelid = self.progoptions.get((progname, target), ('', ''))
+        needles = [target]
+        # For :option:`-foo=bar` search for -foo=bar, -foo= or -foo option directives
+        if '=' in target:
+            needles.append(target[:target.find('=') + 1])
+            needles.append(target[:target.find('=')])
+        for needle in needles:
+            docname, labelid = self.progoptions.get((progname, needle), ('', ''))
+            if docname:
+                break
         if not docname:
             commands = []
             while ws_re.search(target):
diff --git a/sphinx/util/nodes.py b/sphinx/util/nodes.py
index 0646b44e64..f81ef06306 100644
--- a/sphinx/util/nodes.py
+++ b/sphinx/util/nodes.py
@@ -466,7 +466,7 @@ def _make_id(string: str) -> str:
     return str(id)
 
 
-_non_id_chars = re.compile('[^a-zA-Z0-9._]+')
+_non_id_chars = re.compile('[^a-zA-Z0-9._=]+')
 _non_id_at_ends = re.compile('^[-0-9._]+|-+$')
 _non_id_translate = {
     0x00f8: 'o',       # o with stroke
diff --git a/tests/test_util_nodes.py b/tests/test_util_nodes.py
index 14dcdcd586..3fe441b825 100644
--- a/tests/test_util_nodes.py
+++ b/tests/test_util_nodes.py
@@ -189,10 +189,11 @@ def test_clean_astext():
         ('', '_io.StringIO', 'io.StringIO'),  # starts with underscore
         ('', 'ｓｐｈｉｎｘ', 'sphinx'),  # alphabets in unicode fullwidth characters
         ('', '悠好', 'id0'),  # multibytes text (in Chinese)
-        ('', 'Hello=悠好=こんにちは', 'Hello'),  # alphabets and multibytes text
+        ('', 'Hello=悠好=こんにちは', 'Hello=='),  # alphabets and multibytes text
         ('', 'fünf', 'funf'),  # latin1 (umlaut)
         ('', '0sphinx', 'sphinx'),  # starts with number
         ('', 'sphinx-', 'sphinx'),  # ends with hyphen
+        ('', '-foo=bar', 'foo=bar'),  # test option value
     ])
 def test_make_id(app, prefix, term, expected):
     document = create_new_document()