diff --git a/lib/ocaml/baseline/expected.json b/lib/ocaml/baseline/expected.json
index 90b61eb0..d2b6abc9 100644
--- a/lib/ocaml/baseline/expected.json
+++ b/lib/ocaml/baseline/expected.json
@@ -68,6 +68,7 @@
   "fizz_classifier.ml": 540,
   "fizzbuzz.ml": 57,
   "flatten_tree.ml": 28,
+  "lis.ml": 6,
   "list_ops.ml": 30,
   "luhn.ml": 2,
   "mat_mul.ml": 621,
diff --git a/lib/ocaml/baseline/lis.ml b/lib/ocaml/baseline/lis.ml
new file mode 100644
index 00000000..3da1c520
--- /dev/null
+++ b/lib/ocaml/baseline/lis.ml
@@ -0,0 +1,18 @@
+let lis arr =
+  let n = Array.length arr in
+  let dp = Array.make n 1 in
+  for i = 1 to n - 1 do
+    for j = 0 to i - 1 do
+      if arr.(j) < arr.(i) && dp.(j) + 1 > dp.(i) then
+        dp.(i) <- dp.(j) + 1
+    done
+  done;
+  let best = ref 0 in
+  for i = 0 to n - 1 do
+    if dp.(i) > !best then best := dp.(i)
+  done;
+  !best
+
+;;
+
+lis [|10; 22; 9; 33; 21; 50; 41; 60; 80|]
diff --git a/lib/ocaml/parser.sx b/lib/ocaml/parser.sx
index bd2b77d8..92773071 100644
--- a/lib/ocaml/parser.sx
+++ b/lib/ocaml/parser.sx
@@ -468,6 +468,47 @@
                     (advance-tok!)
                     (cond
                       ((at-op? "]") (begin (advance-tok!) (list :list)))
+                      ;; Array literal `[| e1; e2; ...; en |]` desugars to
+                      ;; `Array.of_list [e1; e2; ...; en]`. Empty `[||]`
+                      ;; → `Array.of_list []`.
+                      ((at-op? "|")
+                        (begin
+                          (advance-tok!)
+                          (cond
+                            ((at-op? "|")
+                              (begin
+                                (advance-tok!)
+                                (consume! "op" "]")
+                                (list :app
+                                      (list :field (list :con "Array")
+                                            "of_list")
+                                      (list :list))))
+                            (else
+                              (let
+                                ((items (list)))
+                                (begin
+                                  (append! items (parse-expr-no-seq))
+                                  (define
+                                    aloop
+                                    (fn
+                                      ()
+                                      (when
+                                        (at-op? ";")
+                                        (begin
+                                          (advance-tok!)
+                                          (when
+                                            (not (at-op? "|"))
+                                            (begin
+                                              (append! items
+                                                       (parse-expr-no-seq))
+                                              (aloop)))))))
+                                  (aloop)
+                                  (consume! "op" "|")
+                                  (consume! "op" "]")
+                                  (list :app
+                                        (list :field (list :con "Array")
+                                              "of_list")
+                                        (cons :list items))))))))
                       (else
                         (let
                           ((items (list)))
diff --git a/plans/ocaml-on-sx.md b/plans/ocaml-on-sx.md
index bb56d80e..ba8e479f 100644
--- a/plans/ocaml-on-sx.md
+++ b/plans/ocaml-on-sx.md
@@ -407,6 +407,16 @@ _Newest first._
   binary search tree (`type 'a tree = Leaf | Node of 'a * 'a tree *
   'a tree`) with insert + in-order traversal. Tests parametric ADT,
   recursive match, List.append, List.fold_left.
+- 2026-05-10 Phase 5.1 — array literals + lis.ml baseline (longest
+  increasing subsequence on a 9-element array = 6). Added parser
+  support for `[| e1; e2; ...; en |]` syntax: desugars to
+  `Array.of_list [e1; e2; ...; en]` (which is `ref [...]`). Empty
+  `[||]` → `Array.of_list []`. Tokenizer leaves `[`, `|`, `|`, `]`
+  as separate ops; parser detects `[` followed by `|` to switch to
+  array-literal mode and consumes `|` then `]` at the end.
+  Used in `lis [|10; 22; 9; 33; 21; 50; 41; 60; 80|] = 6`.
+  Tests Array.length, .(i)<-/.(i), nested for + ref.
+  137 baseline programs total.
 - 2026-05-10 Phase 5.1 — josephus.ml baseline (Josephus problem,
   n=50 k=3 → survivor at position 11, 1-indexed). Uses the classic
   recursive formula: J(1, k) = 0; J(n, k) = (J(n-1, k) + k) mod n.