diff --git a/lisp/pcomplete.el b/lisp/pcomplete.el
index d5ffee6ce42..121f4efdb92 100644
--- a/lisp/pcomplete.el
+++ b/lisp/pcomplete.el
@@ -1376,7 +1376,7 @@ OPTIONS should be a list of option strings; if a string ends in
 \"=\", it's an option that accepts a value."
   (lambda (string pred action)
     (pcase action
-      ('nil                               ; try-completion
+      ('nil                             ; try-completion
        (let ((result (try-completion string options pred)))
          ;; If the completion ends in "=", then it's not really
          ;; complete yet: we expect a value after the "=".  Return the
@@ -1385,10 +1385,22 @@ OPTIONS should be a list of option strings; if a string ends in
          (if (and (eq result t) (string-suffix-p "=" string))
              string
            result)))
-      ('t                                 ; all-completions
-       (all-completions string options pred))
-      ('lambda                            ; test-completion
-        (test-completion string options pred)))))
+      ('t                               ; all-completions
+       ;; Don't list completions when the boundary starts after an "=".
+       (unless (and (string-suffix-p "=" string)
+                    (member string options))
+         (all-completions string options pred)))
+      ('lambda                          ; test-completion
+       (test-completion string options pred))
+      (`(boundaries . ,suffix)          ; completion-boundaries
+       ;; As above, if the completion ends in "=", then it's not
+       ;; complete yet.  The completion's boundary should start after
+       ;; the "=" to indicate that that's where subsequent completions
+       ;; will occur.
+       (if (and (string-suffix-p "=" string)
+                (member string options))
+           `(boundaries ,(length string) . ,(length suffix))
+         (completion-boundaries string options pred suffix))))))
 
 ;;; Parsing help messages
 
diff --git a/test/lisp/pcomplete-tests.el b/test/lisp/pcomplete-tests.el
index a5357f18835..95432442cc6 100644
--- a/test/lisp/pcomplete-tests.el
+++ b/test/lisp/pcomplete-tests.el
@@ -96,17 +96,21 @@ usage: git [-v | --version] [-h | --help] [-C <path>] [-c <name>=<value>]
         #("--super-prefix=" 0 1 (pcomplete-annotation "<path>"))
         #("--config-env=" 0 1 (pcomplete-annotation "<name>")))))))
 
-(defun pcomplete-shell-completion (input)
-  "Insert INPUT into shell mode, run completion, and return the result."
-  (with-temp-buffer
-    (shell (current-buffer))
-    (unwind-protect
-        (let ((start (point)))
-          (insert input)
-          (completion-at-point)
-          (buffer-substring start (point)))
-      (let (kill-buffer-query-functions)
-        (kill-buffer (current-buffer))))))
+(defmacro pcomplete-shell-completion (input &rest body)
+  "Insert INPUT into shell mode, run completion, and return the result.
+BODY is a list of extra forms to call after completion (e.g. to choose a
+completion from the minibuffer)."
+  (declare (indent 1))
+  `(with-temp-buffer
+     (shell (current-buffer))
+     (unwind-protect
+         (let ((start (point)))
+           (insert ,input)
+           (completion-at-point)
+           ,@body
+           (buffer-substring start (point)))
+       (let (kill-buffer-query-functions)
+         (kill-buffer (current-buffer))))))
 
 (defun pcomplete/pcmpl-option-test ()
   "Completion for a test command taking long options."
@@ -124,5 +128,21 @@ usage: git [-v | --version] [-h | --help] [-C <path>] [-c <name>=<value>]
   (should (string= (pcomplete-shell-completion "pcmpl-option-test --ver")
                    "pcmpl-option-test --version ")))
 
+(ert-deftest pcomplete-test-long-options/with-value/multiple ()
+  "Test that completing long options taking values doesn't insert a space.
+This tests completing when there are multiple possibilities."
+  (should (string= (pcomplete-shell-completion "pcmpl-option-test --"
+                     (minibuffer-next-completion 1)
+                     (minibuffer-choose-completion))
+                   "pcmpl-option-test --owner=")))
+
+(ert-deftest pcomplete-test-long-options/without-value/multiple ()
+  "Test that completing long options without values inserts a space.
+This tests completing when there are multiple possibilities."
+  (should (string= (pcomplete-shell-completion "pcmpl-option-test --"
+                     (minibuffer-next-completion 2)
+                     (minibuffer-choose-completion))
+                   "pcmpl-option-test --version ")))
+
 (provide 'pcomplete-tests)
 ;;; pcomplete-tests.el ends here