diff --git a/lisp/lib/git.el b/lisp/lib/git.el
new file mode 100644
index 000000000..dc5d82dc1
--- /dev/null
+++ b/lisp/lib/git.el
@@ -0,0 +1,11 @@
+;;; lisp/lib/git.el -*- lexical-binding: t; -*-
+
+;;;###autoload
+(defun doom-git-toplevel (&rest segments)
+  "Return the path to the current repo's root."
+  (cl-destructuring-bind (code . output)
+      (doom-call-process "git" "rev-parse" "--show-toplevel")
+    (if (zerop code)
+        (apply #'file-name-concat output segments)
+      ;; TODO throw stderr as error
+      (user-error "Not in a git repo: %s" default-directory))))