diff --git a/tests/baselines/reference/unionTypeEquivalence.js b/tests/baselines/reference/unionTypeEquivalence.js
new file mode 100644
index 00000000000..3698ecd2f92
--- /dev/null
+++ b/tests/baselines/reference/unionTypeEquivalence.js
@@ -0,0 +1,54 @@
+//// [unionTypeEquivalence.ts]
+// A | B is equivalent to A if B is a subtype of A
+class C { }
+class D extends C { }
+var x: C;
+var x : C | D;
+
+// A | B is equivalent to B | A.
+var y: string | number;
+var y : number | string;
+
+// AB | C is equivalent to A | BC, where AB is A | B and BC is B | C.
+var z : string | number | boolean;
+var z : (string | number) | boolean;
+var z : string | (number | boolean);
+var AB : string | number;
+var BC : number | boolean;
+var z1: typeof AB | boolean;
+var z1: string | typeof BC;
+
+
+//// [unionTypeEquivalence.js]
+var __extends = this.__extends || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    __.prototype = b.prototype;
+    d.prototype = new __();
+};
+// A | B is equivalent to A if B is a subtype of A
+var C = (function () {
+    function C() {
+    }
+    return C;
+})();
+var D = (function (_super) {
+    __extends(D, _super);
+    function D() {
+        _super.apply(this, arguments);
+    }
+    return D;
+})(C);
+var x;
+var x;
+// A | B is equivalent to B | A.
+var y;
+var y;
+// AB | C is equivalent to A | BC, where AB is A | B and BC is B | C.
+var z;
+var z;
+var z;
+var AB;
+var BC;
+var z1;
+var z1;
diff --git a/tests/baselines/reference/unionTypeEquivalence.types b/tests/baselines/reference/unionTypeEquivalence.types
new file mode 100644
index 00000000000..53e95659120
--- /dev/null
+++ b/tests/baselines/reference/unionTypeEquivalence.types
@@ -0,0 +1,49 @@
+=== tests/cases/conformance/types/union/unionTypeEquivalence.ts ===
+// A | B is equivalent to A if B is a subtype of A
+class C { }
+>C : C
+
+class D extends C { }
+>D : D
+>C : C
+
+var x: C;
+>x : C
+>C : C
+
+var x : C | D;
+>x : C
+>C : C
+>D : D
+
+// A | B is equivalent to B | A.
+var y: string | number;
+>y : string | number
+
+var y : number | string;
+>y : string | number
+
+// AB | C is equivalent to A | BC, where AB is A | B and BC is B | C.
+var z : string | number | boolean;
+>z : string | number | boolean
+
+var z : (string | number) | boolean;
+>z : string | number | boolean
+
+var z : string | (number | boolean);
+>z : string | number | boolean
+
+var AB : string | number;
+>AB : string | number
+
+var BC : number | boolean;
+>BC : number | boolean
+
+var z1: typeof AB | boolean;
+>z1 : string | number | boolean
+>AB : string | number
+
+var z1: string | typeof BC;
+>z1 : string | number | boolean
+>BC : number | boolean
+
diff --git a/tests/cases/conformance/types/union/unionTypeEquivalence.ts b/tests/cases/conformance/types/union/unionTypeEquivalence.ts
new file mode 100644
index 00000000000..0905fde17f8
--- /dev/null
+++ b/tests/cases/conformance/types/union/unionTypeEquivalence.ts
@@ -0,0 +1,18 @@
+// A | B is equivalent to A if B is a subtype of A
+class C { }
+class D extends C { }
+var x: C;
+var x : C | D;
+
+// A | B is equivalent to B | A.
+var y: string | number;
+var y : number | string;
+
+// AB | C is equivalent to A | BC, where AB is A | B and BC is B | C.
+var z : string | number | boolean;
+var z : (string | number) | boolean;
+var z : string | (number | boolean);
+var AB : string | number;
+var BC : number | boolean;
+var z1: typeof AB | boolean;
+var z1: string | typeof BC;