diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 3e3a37f6da..a8283d0d4a 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -1246,12 +1246,45 @@ xref-matches-in-directory
 (declare-function tramp-tramp-file-p "tramp")
 (declare-function tramp-file-local-name "tramp")
 
+;; '-s' because 'git ls-files' can output broken symlinks.
+(defconst xref-grep-search-template
+  "xargs -0 grep <C> -snHE -e <R>"
+  "Use Grep to search a list of files piped from stdin.")
+
+;; See https://github.com/BurntSushi/ripgrep/issues/152 on
+;; the subject of non-deterministic output.
+(defconst xref-ripgrep-search-template
+  "xargs -0 rg <C> -nH --no-messages -g '!*/' -e <R> | sort -t: -k1 -k2n"
+  "Use ripgrep to search a list of files piped from stdin.
+
+The arguments are chosen carefully so that the output format is
+compatible with Grep.  As well as its '-s' argument.
+
+Note: by default, ripgrep's output order is non-deterministic
+because it does the search in parallel.  You can use the template
+without the '| sort ...' part if GNU sort is not available on
+your system and/or stable ordering is not important to you.")
+
+(defcustom xref-search-command-template xref-grep-search-template
+  "Command template to search a list of files piped from stdin.
+
+Allowed fields:
+
+  <C> for extra arguments such as -i and --color
+  <R> for the regexp itself (in Extended format)"
+  :type `(choice
+          (const :tag "Use Grep" ,xref-grep-search-template)
+          (const :tag "Use ripgrep" ,xref-ripgrep-search-template)
+          (string :tag "User defined")))
+
 ;;;###autoload
 (defun xref-matches-in-files (regexp files)
   "Find all matches for REGEXP in FILES.
 Return a list of xref values.
 FILES must be a list of absolute file names."
   (cl-assert (consp files))
+  (require 'grep)
+  (defvar grep-highlight-matches)
   (pcase-let*
       ((output (get-buffer-create " *project grep output*"))
        (`(,grep-re ,file-group ,line-group . ,_) (car grep-regexp-alist))
@@ -1261,13 +1294,12 @@ xref-matches-in-files
        ;; first file is remote, they all are, and on the same host.
        (dir (file-name-directory (car files)))
        (remote-id (file-remote-p dir))
-       ;; 'git ls-files' can output broken symlinks.
-       (command (format "xargs -0 grep %s -snHE -e %s"
-                        (if (and case-fold-search
-                                 (isearch-no-upper-case-p regexp t))
-                            "-i"
-                          "")
-                        (shell-quote-argument (xref--regexp-to-extended regexp)))))
+       ;; The 'auto' default would be fine too, but ripgrep can't handle
+       ;; the options we pass in that case.
+       (grep-highlight-matches)
+       (command (grep-expand-template xref-search-command-template
+                                      (xref--regexp-to-extended regexp)
+                                      regexp)))
     (when remote-id
       (require 'tramp)
       (setq files (mapcar