diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index fdb5fabfa0e..e70d1956c98 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -275,16 +275,16 @@ def build_specific(self, filenames: List[str]) -> None:
         for filename in filenames:
             filename = path.normpath(path.abspath(filename))
 
+            if not path.isfile(filename):
+                logger.warning(__('file %r given on command line does not exist, '),
+                               filename)
+                continue
+
             if not filename.startswith(self.srcdir):
                 logger.warning(__('file %r given on command line is not under the '
                                   'source directory, ignoring'), filename)
                 continue
 
-            if not path.isfile(filename):
-                logger.warning(__('file %r given on command line does not exist, '
-                                  'ignoring'), filename)
-                continue
-
             docname = self.env.path2doc(filename)
             if not docname:
                 logger.warning(__('file %r given on command line is not a valid '
diff --git a/sphinx/cmd/build.py b/sphinx/cmd/build.py
index d08ad1d926f..6cadefe3bb9 100644
--- a/sphinx/cmd/build.py
+++ b/sphinx/cmd/build.py
@@ -209,16 +209,7 @@ def build_main(argv: List[str] = sys.argv[1:]) -> int:
     if not args.doctreedir:
         args.doctreedir = os.path.join(args.outputdir, '.doctrees')
 
-    # handle remaining filename arguments
-    filenames = args.filenames
-    missing_files = []
-    for filename in filenames:
-        if not os.path.isfile(filename):
-            missing_files.append(filename)
-    if missing_files:
-        parser.error(__('cannot find files %r') % missing_files)
-
-    if args.force_all and filenames:
+    if args.force_all and args.filenames:
         parser.error(__('cannot combine -a option and filenames'))
 
     if args.color == 'no' or (args.color == 'auto' and not color_terminal()):
@@ -276,7 +267,7 @@ def build_main(argv: List[str] = sys.argv[1:]) -> int:
                          warning, args.freshenv, args.warningiserror,
                          args.tags, args.verbosity, args.jobs, args.keep_going,
                          args.pdb)
-            app.build(args.force_all, filenames)
+            app.build(args.force_all, args.filenames)
             return app.statuscode
     except (Exception, KeyboardInterrupt) as exc:
         handle_exception(app, args, exc, error)