diff --git a/zerver/tests/test_upload.py b/zerver/tests/test_upload.py
index 58a4c81b1f..9cfa35b4bf 100644
--- a/zerver/tests/test_upload.py
+++ b/zerver/tests/test_upload.py
@@ -543,7 +543,8 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
             self.logout()
 
     def test_serve_local(self) -> None:
-        def check_xsend_links(name: Text, name_str_for_test: Text) -> None:
+        def check_xsend_links(name: Text, name_str_for_test: Text,
+                              content_disposition: Text='') -> None:
             with self.settings(SENDFILE_BACKEND='sendfile.backends.nginx'):
                 _get_sendfile.clear()  # To clearout cached version of backend from djangosendfile
                 self.login(self.example_email("hamlet"))
@@ -559,9 +560,20 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
                 self.assertEqual(response['X-Accel-Redirect'],
                                  '/serve_uploads/../../'  + test_upload_dir +
                                  '/files/' + fp_path + '/' + name_str_for_test)
+                if content_disposition != '':
+                    self.assertIn('attachment;', response['Content-disposition'])
+                    self.assertIn(content_disposition, response['Content-disposition'])
+                else:
+                    self.assertEqual(response.get('Content-disposition'), None)
 
-        check_xsend_links('zulip.txt', 'zulip.txt')
-        check_xsend_links('áéБД.txt', '%C3%A1%C3%A9%D0%91%D0%94.txt')
+        check_xsend_links('zulip.txt', 'zulip.txt', "filename*=UTF-8''zulip.txt")
+        check_xsend_links('áéБД.txt', '%C3%A1%C3%A9%D0%91%D0%94.txt',
+                          "filename*=UTF-8''%C3%A1%C3%A9%D0%91%D0%94.txt")
+        check_xsend_links('zulip.html', 'zulip.html', "filename*=UTF-8''zulip.html")
+        check_xsend_links('zulip.sh', 'zulip.sh', "filename*=UTF-8''zulip.sh")
+        check_xsend_links('zulip.jpeg', 'zulip.jpeg')
+        check_xsend_links('áéБД.pdf', '%C3%A1%C3%A9%D0%91%D0%94.pdf')
+        check_xsend_links('zulip', 'zulip', "filename*=UTF-8''zulip")
 
     def tearDown(self) -> None:
         destroy_uploads()
diff --git a/zerver/views/upload.py b/zerver/views/upload.py
index cfcd95dc76..a5d5eb7c74 100644
--- a/zerver/views/upload.py
+++ b/zerver/views/upload.py
@@ -13,6 +13,7 @@ from zerver.lib.validator import check_bool
 from zerver.models import UserProfile, validate_attachment_request
 from django.conf import settings
 from sendfile import sendfile
+from mimetypes import guess_type
 
 def serve_s3(request: HttpRequest, url_path: str) -> HttpResponse:
     uri = get_signed_upload_url(url_path)
@@ -22,7 +23,30 @@ def serve_local(request: HttpRequest, path_id: str) -> HttpResponse:
     local_path = get_local_file_path(path_id)
     if local_path is None:
         return HttpResponseNotFound('<p>File not found</p>')
-    return sendfile(request, local_path)
+
+    # Here we determine whether a browser should treat the file like
+    # an attachment (and thus clicking a link to it should download)
+    # or like a link (and thus clicking a link to it should display it
+    # in a browser tab).  This is controlled by the
+    # Content-Disposition header; `django-sendfile` sends the
+    # attachment-style version of that header if and only if the
+    # attachment argument is passed to it.  For attachments,
+    # django-sendfile sets the response['Content-disposition'] like
+    # this: `attachment; filename="b'zulip.txt'"; filename*=UTF-8''zulip.txt`.
+    #
+    # The "filename" field (used to name the file when downloaded) is
+    # unreliable because it doesn't have a well-defined encoding; the
+    # newer filename* field takes precedence, since it uses a
+    # consistent format (urlquoted).  For more details on filename*
+    # and filename, see the below docs:
+    # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
+    attachment = True
+    file_type = guess_type(local_path)[0]
+    if file_type is not None and (file_type.startswith("image/") or
+                                  file_type == "application/pdf"):
+        attachment = False
+
+    return sendfile(request, local_path, attachment=attachment)
 
 @has_request_variables
 def serve_file_backend(request: HttpRequest, user_profile: UserProfile,