diff --git a/packages/compiler/src/backend/llvm/expr-dynamic.ts b/packages/compiler/src/backend/llvm/expr-dynamic.ts
index 849715ab0..55bbb828b 100644
--- a/packages/compiler/src/backend/llvm/expr-dynamic.ts
+++ b/packages/compiler/src/backend/llvm/expr-dynamic.ts
@@ -31,7 +31,8 @@ import { elemAccess, vAdapters } from "./shapes.js";
 import { LlvmUnsupportedError } from "./unsupported.js";
 import type { LlvmEmitterContext, ExprOf, LlValue } from "./expr-context.js";
 import { emitUnionWiden } from "./expr-records.js";
-import { emitJsIcMethod, jsIcMethods } from "./js-ic.js";
+import { emitJsIcLiteralMember, emitJsIcMethod, jsIcMethods } from "./js-ic.js";
+import { jsIcLiteralKey } from "../../ir/js-ic.js";
 import { DYN_BUFFER_METHODS } from "../../ir/runtime-features.js";
 
 export function emitDynamicExpr(
@@ -316,9 +317,14 @@ export function emitDynamicExpr(
       const obj = B.tmp();
       B.line(`${obj} = call ptr @scr_dyn_new_obj()`);
       const out = host.own({ name: obj, type: e.type });
+      const cached = jsIcMethods(host);
       for (const f of e.fields ?? []) {
         const k = emitBorrowedInput(host, f.key);
         const v = emitBorrowedInput(host, f.value);
+        if (cached && jsIcLiteralKey(f.key) !== null) {
+          emitJsIcLiteralMember(host, obj, k.name, v.name);
+          continue;
+        }
         B.line(
           `call void @${f.key.type.kind === "dyn" ? "scr_dyn_key_set_computed" : "scr_dyn_key_set"}(ptr ${obj}, ptr ${k.name}, ptr ${v.name})`,
         );
diff --git a/packages/compiler/src/backend/llvm/js-ic.ts b/packages/compiler/src/backend/llvm/js-ic.ts
index b69d3199d..11b894a60 100644
--- a/packages/compiler/src/backend/llvm/js-ic.ts
+++ b/packages/compiler/src/backend/llvm/js-ic.ts
@@ -14,6 +14,8 @@
  *   keyed  dense array element at an integral number key: inline;
  *          otherwise scr_js_keyed_probe (string keys of ordinary objects)
  *   method dynInvoke's method read: scr_js_load_probe
+ *   literal an object literal's constant-key member: scr_js_store_probe,
+ *          else scr_dyn_key_set
  *
  * A probe that cannot answer from plain data leaves everything untouched,
  * and the site calls its helper (or the generic runtime entry), which
@@ -838,6 +840,27 @@ function emitKeyed(host: Host, e: ExprOf<"call">, callee: IrFunction): LlValue {
   return host.own({ name: out, type: e.type });
 }
 
+/** One member of an object literal (ir/js-ic.ts jsIcLiteralKey) added to
+ * the fresh object `obj` through the site's store cache, else with
+ * scr_dyn_key_set. The key and value are borrowed. */
+export function emitJsIcLiteralMember(host: Host, obj: string, key: string, value: string): void {
+  const B = host.B;
+  const ic = host.jsIcSite();
+  host.declare(`declare zeroext i1 @scr_js_store_probe(ptr, ptr, ptr, ptr)`);
+  const done = B.tmp();
+  B.line(
+    `${done} = call zeroext i1 @scr_js_store_probe(ptr ${obj}, ptr ${key}, ptr ${value}, ptr ${ic})`,
+  );
+  const slow = B.newLabel("icl.slow");
+  const join = B.newLabel("icl.j");
+  B.condBr(done, join, slow);
+  B.startBlock(slow);
+  B.line(`call void @scr_dyn_key_set(ptr ${obj}, ptr ${key}, ptr ${value})`);
+  host.emitPendingCheck();
+  B.br(join);
+  B.startBlock(join);
+}
+
 /** dynInvoke's method read on an ordinary object through the site's
  * cache, else scr_dyn_prepare_method. Returns the owned method (or NULL,
  * which scr_dyn_invoke_prepared_id answers with the full dispatch). */
diff --git a/packages/compiler/src/ir/js-ic.test.ts b/packages/compiler/src/ir/js-ic.test.ts
index f5391b83e..35de18085 100644
--- a/packages/compiler/src/ir/js-ic.test.ts
+++ b/packages/compiler/src/ir/js-ic.test.ts
@@ -311,6 +311,23 @@ test("a function holds a site when it calls a classified helper or dispatches a
   expect(hasJsIcSite({ ...caller, name: "%init.0" }, sites)).toBe(true);
 });
 
+test("a function holds a site when an object literal has a constant-key member", () => {
+  const sites = sitesOf();
+  const literal = (key: IrExpr): IrFunction =>
+    helper(
+      "f",
+      ["o"],
+      [ret({ kind: "dynObjLit", fields: [{ key, value: ref("o") }], type: DYN, loc })],
+    );
+  expect(hasJsIcSite(literal(str("x")), sites)).toBe(true);
+  // `__proto__` sets the prototype, and a computed key has no constant
+  // name: both keep the generic member store.
+  expect(hasJsIcSite(literal(str("__proto__")), sites)).toBe(false);
+  expect(hasJsIcSite(literal(ref("k")), sites)).toBe(false);
+  // Module initializers build their literals once.
+  expect(hasJsIcSite({ ...literal(str("x")), name: "%init.0" }, sites)).toBe(false);
+});
+
 test("bag helpers that exit early for values no class branch matches are still the receiver", () => {
   /** `if (!<test>(v)) return <value>`: the class tables' early exit. */
   const exit = (test: "classCapsule" | "funcKind", value: IrExpr, negated = true): IrStmt => ({
diff --git a/packages/compiler/src/ir/js-ic.ts b/packages/compiler/src/ir/js-ic.ts
index 48019636a..5a483c585 100644
--- a/packages/compiler/src/ir/js-ic.ts
+++ b/packages/compiler/src/ir/js-ic.ts
@@ -296,20 +296,33 @@ function unwrapFromDyn(e: IrExpr | null | undefined): IrExpr | null {
   return e;
 }
 
-/** Whether a function holds a cache site: a call to a classified helper or
- * a method dispatch. */
+/** Whether a function holds a cache site: a call to a classified helper,
+ * a method dispatch, or an object literal member with a constant key. */
 export function hasJsIcSite(fn: IrFunction, sites: JsIcSites): boolean {
   const methods = jsIcMethodSites(fn.name);
   return !everyStmtList(fn.body, {
     expr: (e) =>
       !(
         (methods && e.kind === "dynInvoke") ||
+        (methods &&
+          e.kind === "dynObjLit" &&
+          (e.fields ?? []).some((f) => jsIcLiteralKey(f.key) !== null)) ||
         (e.kind === "call" && sites.site(e.callee) !== null)
       ),
     stmt: () => true,
   });
 }
 
+/** The key of an object literal member that its site adds through the
+ * store cache: a constant string other than `__proto__`, or null. The
+ * literal starts as an empty object with the default prototype, so each
+ * such member appends one data property, and the site caches the shape
+ * transition and shares the key bytes the shape holds. Module
+ * initializers have no literal sites (jsIcMethodSites). */
+export function jsIcLiteralKey(key: IrExpr): string | null {
+  return key.kind === "strLit" && key.value !== "__proto__" ? key.value : null;
+}
+
 /** Whether method dispatch in a function goes through caches. Module
  * initializers (`%init.N`) run once, and the methods they call at top level
  * are overwhelmingly registrations on native handles (`worker.on(...)`,
diff --git a/packages/compiler/test/js-ic-emission.test.ts b/packages/compiler/test/js-ic-emission.test.ts
index 15e8e92bc..79342e99d 100644
--- a/packages/compiler/test/js-ic-emission.test.ts
+++ b/packages/compiler/test/js-ic-emission.test.ts
@@ -64,6 +64,37 @@ console.log(read(o), at(dyn([5, 6]), 1), call(o), o.n);
   }
 });
 
+test("object literal members with constant keys add through store caches", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "scriptc-js-ic-literal-"));
+  try {
+    const entry = join(dir, "main.js");
+    const outPath = join(dir, "main.ir.json");
+    await writeFile(
+      entry,
+      `
+function make(v, k) { return { a: v, b: 2, [k]: 3 }; }
+var top = { t: 1 };
+console.log(JSON.stringify(make(1, "c")), top.t);
+`,
+    );
+    const result = await compile(entry, { outDir: dir, outPath, outputKind: "ir" });
+    if (!result.ok)
+      throw new Error(result.diagnostics.map((d) => `${d.code}: ${d.message}`).join("\n"));
+    const mod = deserializeModule(await readFile(outPath, "utf8"));
+    expect(moduleUsesDynTier(mod)).toBe(true);
+    const llvm = emitLlvmModule(mod);
+    const make = body(llvm, "make");
+    // Each constant-key member tries its site's store cache first and
+    // falls back to the generic member store; the computed key keeps the
+    // generic store only.
+    expect(make.match(/@scr_js_store_probe\(/g)).toHaveLength(2);
+    expect(make.match(/@scr_dyn_key_set\(/g)).toHaveLength(2);
+    expect(make).toContain("@scr_dyn_key_set_computed(");
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
 test("property sites keep their caches in programs that declare classes and subclasses", async () => {
   const dir = await mkdtemp(join(tmpdir(), "scriptc-js-ic-class-"));
   try {
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/object-literal-members.mjs.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/object-literal-members.mjs.json
new file mode 100644
index 000000000..f1f9017ac
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/object-literal-members.mjs.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/object-literal-members.mjs"
+ ],
+ "diags": []
+}
diff --git a/tests/corpus/object-literal-members.mjs b/tests/corpus/object-literal-members.mjs
new file mode 100644
index 000000000..4bd211435
--- /dev/null
+++ b/tests/corpus/object-literal-members.mjs
@@ -0,0 +1,67 @@
+// Object literals built in untyped functions, many times through the same
+// sites: key order (integer-like keys first), members named
+// like Object.prototype members and Error fields, __proto__ members, wide
+// literals, literals that differ only in a later member, and objects
+// changed after they are built.
+function point(x, y) {
+  return { x, y, label: "p" + x };
+}
+function ordered(i) {
+  return { b: i, 2: "two", a: i + 1, 1: "one", "01": "zero-one" };
+}
+function named(i) {
+  return { constructor: i, toString: "s" + i, message: "m" + i, name: "n" + i, code: i, stack: "st" };
+}
+function withProto(proto, i) {
+  if (proto === null) return { __proto__: null, own: i };
+  const o = { own: i };
+  Object.setPrototypeOf(o, proto);
+  return o;
+}
+function wide(i) {
+  return {
+    k0: i, k1: i, k2: i, k3: i, k4: i, k5: i, k6: i, k7: i, k8: i, k9: i,
+    k10: i, k11: i, k12: i, k13: i, k14: i, k15: i, k16: i, k17: i, k18: i, k19: i,
+    k20: i, k21: i, k22: i, k23: i, k24: i, k25: i, k26: i, k27: i, k28: i, k29: i,
+    k30: i, k31: i, k32: i, k33: i, k34: i, k35: i, k36: i, k37: i, k38: i, k39: i,
+    k40: i, k41: i, k42: i, k43: i, k44: i, k45: i, k46: i, k47: i, k48: i, k49: i,
+    k50: i, k51: i, k52: i, k53: i, k54: i, k55: i, k56: i, k57: i, k58: i, k59: i,
+    k60: i, k61: i, k62: i, k63: i, k64: i, k65: i, k66: i, k67: i, k68: i, k69: i,
+  };
+}
+function variant(i) {
+  const head = { kind: "v", n: i };
+  return i % 2 ? { ...head, odd: true } : { ...head, even: true, n: -i };
+}
+
+let sum = 0;
+const points = [];
+for (let i = 0; i < 2000; i++) {
+  const p = point(i, i * 2);
+  sum += p.x + p.y;
+  if (i % 500 === 0) points.push(p);
+}
+points[0].z = 9;
+delete points[1].label;
+console.log(sum, JSON.stringify(points), Object.keys(points[2]).join());
+
+const o = [ordered(1), ordered(2)];
+console.log(Object.keys(o[1]).join(), JSON.stringify(o[0]), o[1]["01"], o[1][1]);
+
+const n = [named(1), named(2)];
+console.log(JSON.stringify(n[1]), typeof n[0].toString, n[1].constructor, n[1] instanceof Error);
+
+const proto = { greet() { return "hi " + this.own; } };
+const w = [withProto(proto, 1), withProto(proto, 2), withProto(null, 3)];
+console.log(w[1].greet(), Object.getPrototypeOf(w[0]) === proto, Object.getPrototypeOf(w[2]), Object.keys(w[1]).join());
+
+let wideSum = 0;
+for (let i = 0; i < 50; i++) {
+  const big = wide(i);
+  wideSum += big.k0 + big.k69;
+}
+console.log(wideSum, Object.keys(wide(1)).length, Object.keys(wide(2))[69]);
+
+const v = [];
+for (let i = 0; i < 6; i++) v.push(variant(i));
+console.log(JSON.stringify(v));
diff --git a/tests/harness/corpus-costs/object-literal-members.mjs.json b/tests/harness/corpus-costs/object-literal-members.mjs.json
new file mode 100644
index 000000000..882d60088
--- /dev/null
+++ b/tests/harness/corpus-costs/object-literal-members.mjs.json
@@ -0,0 +1 @@
+{ "plain": 3565, "san": 6266 }
diff --git a/tests/harness/library-mode.test.ts b/tests/harness/library-mode.test.ts
index 4c1b96b37..4a3d4c390 100644
--- a/tests/harness/library-mode.test.ts
+++ b/tests/harness/library-mode.test.ts
@@ -386,7 +386,7 @@ globals: undefined fenced
     const run = runProbe(probe);
     expect(run.signal).toBeNull();
     expect(run.status).toBe(0);
-    expect(run.stdout).toBe("run: 20000\n".repeat(3));
+    expect(run.stdout).toBe("run: 40000\n".repeat(3));
   });
 
   /* ── K5/K6/K7: the trap channel ──────────────────────────────────────── */
@@ -614,7 +614,7 @@ survived, sink_calls=1
     const run = runProbe(probe);
     expect(run.signal).toBeNull();
     expect(run.status).toBe(0);
-    expect(run.stdout).toBe("run: 20000\n".repeat(3));
+    expect(run.stdout).toBe("run: 40000\n".repeat(3));
   });
 
   platformTest("K10: K5/K7 under ASan", async () => {
diff --git a/tests/library-mode/js-ic-sessions/work.mjs b/tests/library-mode/js-ic-sessions/work.mjs
index 5c1afcd18..e6c4a2fc3 100644
--- a/tests/library-mode/js-ic-sessions/work.mjs
+++ b/tests/library-mode/js-ic-sessions/work.mjs
@@ -1,6 +1,6 @@
 // Dynamic-tier property caches across library sessions: objects built empty
-// and filled through untyped stores, read back through untyped loads, and a
-// class instance at the same kind of sites. Each session must start with
+// and filled through untyped stores or built by object literals, read back
+// through untyped loads, and a class instance at the same kind of sites. Each session must start with
 // empty caches, since the shapes their entries named are freed when the
 // previous session ends.
 class Box {
@@ -13,6 +13,9 @@ function fill(o, n) {
   o.b = n + 1;
   return o;
 }
+function pair(n) {
+  return { a: n, b: n + 1 };
+}
 function sum(o) {
   return o.a + o.b;
 }
@@ -21,6 +24,6 @@ function unbox(b) {
 }
 export function runAll() {
   let total = 0;
-  for (let i = 0; i < 100; i++) total += sum(fill({}, i));
+  for (let i = 0; i < 100; i++) total += sum(fill({}, i)) + sum(pair(i));
   return total + unbox(new Box(total));
 }