diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index e1daa8977f0..ac424a9d028 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -262,6 +262,11 @@ help-fns--describe-function-or-command-prompt
                   fn))
     (list fn)))
 
+(defun help-fns--setup-xref-backend ()
+  (add-hook 'xref-backend-functions #'elisp--xref-backend nil t)
+  (setq-local project-vc-external-roots-function #'elisp-load-path-roots)
+  (setq-local semantic-symref-filepattern-alist '((help-mode "*.el"))))
+
 ;;;###autoload
 (defun describe-function (function)
   "Display the full documentation of FUNCTION (a symbol).
@@ -287,6 +292,7 @@ describe-function
 
     (save-excursion
       (with-help-window (help-buffer)
+        (help-fns--setup-xref-backend)
         (if (get function 'reader-construct)
             (princ function)
           (prin1 function))
@@ -1348,6 +1354,8 @@ describe-variable
 	      (prin1 variable)
 	      (setq file-name (find-lisp-object-file-name variable 'defvar))
 
+              (help-fns--setup-xref-backend)
+
 	      (princ (if file-name
 		         (progn
 		           (princ (format-message
diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index 63bd685af91..2f931daedc7 100644
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -1049,7 +1049,9 @@ xref-backend-definitions
   (let ((sym (intern-soft identifier)))
     (when sym
       (let* ((pos (get-text-property 0 'pos identifier))
-             (namespace (if pos
+             (namespace (if (and pos
+                                 ;; Reusing it in Help Mode.
+                                 (derived-mode-p 'emacs-lisp-mode))
                             (elisp--xref-infer-namespace pos)
                           'any))
              (defs (elisp--xref-find-definitions sym)))