diff --git a/tests/baselines/reference/narrowTypeByInstanceof.js b/tests/baselines/reference/narrowTypeByInstanceof.js
new file mode 100644
index 00000000000..11f55089bda
--- /dev/null
+++ b/tests/baselines/reference/narrowTypeByInstanceof.js
@@ -0,0 +1,53 @@
+//// [narrowTypeByInstanceof.ts]
+    class Match {
+        public range(): any {
+            return undefined;
+        }
+    }
+
+    class FileMatch {
+        public resource(): any {
+            return undefined;
+        }
+    }
+
+type FileMatchOrMatch = FileMatch | Match;
+
+
+let elementA: FileMatchOrMatch, elementB: FileMatchOrMatch;
+
+if (elementA instanceof FileMatch && elementB instanceof FileMatch) {
+    let a = elementA.resource().path;
+    let b = elementB.resource().path;
+} else if (elementA instanceof Match && elementB instanceof Match) {
+    let a = elementA.range();
+    let b = elementB.range();
+}
+
+
+//// [narrowTypeByInstanceof.js]
+var Match = (function () {
+    function Match() {
+    }
+    Match.prototype.range = function () {
+        return undefined;
+    };
+    return Match;
+})();
+var FileMatch = (function () {
+    function FileMatch() {
+    }
+    FileMatch.prototype.resource = function () {
+        return undefined;
+    };
+    return FileMatch;
+})();
+var elementA, elementB;
+if (elementA instanceof FileMatch && elementB instanceof FileMatch) {
+    var a = elementA.resource().path;
+    var b = elementB.resource().path;
+}
+else if (elementA instanceof Match && elementB instanceof Match) {
+    var a = elementA.range();
+    var b = elementB.range();
+}
diff --git a/tests/baselines/reference/narrowTypeByInstanceof.symbols b/tests/baselines/reference/narrowTypeByInstanceof.symbols
new file mode 100644
index 00000000000..3e620fd105c
--- /dev/null
+++ b/tests/baselines/reference/narrowTypeByInstanceof.symbols
@@ -0,0 +1,72 @@
+=== tests/cases/compiler/narrowTypeByInstanceof.ts ===
+    class Match {
+>Match : Symbol(Match, Decl(narrowTypeByInstanceof.ts, 0, 0))
+
+        public range(): any {
+>range : Symbol(range, Decl(narrowTypeByInstanceof.ts, 0, 17))
+
+            return undefined;
+>undefined : Symbol(undefined)
+        }
+    }
+
+    class FileMatch {
+>FileMatch : Symbol(FileMatch, Decl(narrowTypeByInstanceof.ts, 4, 5))
+
+        public resource(): any {
+>resource : Symbol(resource, Decl(narrowTypeByInstanceof.ts, 6, 21))
+
+            return undefined;
+>undefined : Symbol(undefined)
+        }
+    }
+
+type FileMatchOrMatch = FileMatch | Match;
+>FileMatchOrMatch : Symbol(FileMatchOrMatch, Decl(narrowTypeByInstanceof.ts, 10, 5))
+>FileMatch : Symbol(FileMatch, Decl(narrowTypeByInstanceof.ts, 4, 5))
+>Match : Symbol(Match, Decl(narrowTypeByInstanceof.ts, 0, 0))
+
+
+let elementA: FileMatchOrMatch, elementB: FileMatchOrMatch;
+>elementA : Symbol(elementA, Decl(narrowTypeByInstanceof.ts, 15, 3))
+>FileMatchOrMatch : Symbol(FileMatchOrMatch, Decl(narrowTypeByInstanceof.ts, 10, 5))
+>elementB : Symbol(elementB, Decl(narrowTypeByInstanceof.ts, 15, 31))
+>FileMatchOrMatch : Symbol(FileMatchOrMatch, Decl(narrowTypeByInstanceof.ts, 10, 5))
+
+if (elementA instanceof FileMatch && elementB instanceof FileMatch) {
+>elementA : Symbol(elementA, Decl(narrowTypeByInstanceof.ts, 15, 3))
+>FileMatch : Symbol(FileMatch, Decl(narrowTypeByInstanceof.ts, 4, 5))
+>elementB : Symbol(elementB, Decl(narrowTypeByInstanceof.ts, 15, 31))
+>FileMatch : Symbol(FileMatch, Decl(narrowTypeByInstanceof.ts, 4, 5))
+
+    let a = elementA.resource().path;
+>a : Symbol(a, Decl(narrowTypeByInstanceof.ts, 18, 7))
+>elementA.resource : Symbol(FileMatch.resource, Decl(narrowTypeByInstanceof.ts, 6, 21))
+>elementA : Symbol(elementA, Decl(narrowTypeByInstanceof.ts, 15, 3))
+>resource : Symbol(FileMatch.resource, Decl(narrowTypeByInstanceof.ts, 6, 21))
+
+    let b = elementB.resource().path;
+>b : Symbol(b, Decl(narrowTypeByInstanceof.ts, 19, 7))
+>elementB.resource : Symbol(FileMatch.resource, Decl(narrowTypeByInstanceof.ts, 6, 21))
+>elementB : Symbol(elementB, Decl(narrowTypeByInstanceof.ts, 15, 31))
+>resource : Symbol(FileMatch.resource, Decl(narrowTypeByInstanceof.ts, 6, 21))
+
+} else if (elementA instanceof Match && elementB instanceof Match) {
+>elementA : Symbol(elementA, Decl(narrowTypeByInstanceof.ts, 15, 3))
+>Match : Symbol(Match, Decl(narrowTypeByInstanceof.ts, 0, 0))
+>elementB : Symbol(elementB, Decl(narrowTypeByInstanceof.ts, 15, 31))
+>Match : Symbol(Match, Decl(narrowTypeByInstanceof.ts, 0, 0))
+
+    let a = elementA.range();
+>a : Symbol(a, Decl(narrowTypeByInstanceof.ts, 21, 7))
+>elementA.range : Symbol(Match.range, Decl(narrowTypeByInstanceof.ts, 0, 17))
+>elementA : Symbol(elementA, Decl(narrowTypeByInstanceof.ts, 15, 3))
+>range : Symbol(Match.range, Decl(narrowTypeByInstanceof.ts, 0, 17))
+
+    let b = elementB.range();
+>b : Symbol(b, Decl(narrowTypeByInstanceof.ts, 22, 7))
+>elementB.range : Symbol(Match.range, Decl(narrowTypeByInstanceof.ts, 0, 17))
+>elementB : Symbol(elementB, Decl(narrowTypeByInstanceof.ts, 15, 31))
+>range : Symbol(Match.range, Decl(narrowTypeByInstanceof.ts, 0, 17))
+}
+
diff --git a/tests/baselines/reference/narrowTypeByInstanceof.types b/tests/baselines/reference/narrowTypeByInstanceof.types
new file mode 100644
index 00000000000..b98b1e4d234
--- /dev/null
+++ b/tests/baselines/reference/narrowTypeByInstanceof.types
@@ -0,0 +1,86 @@
+=== tests/cases/compiler/narrowTypeByInstanceof.ts ===
+    class Match {
+>Match : Match
+
+        public range(): any {
+>range : () => any
+
+            return undefined;
+>undefined : undefined
+        }
+    }
+
+    class FileMatch {
+>FileMatch : FileMatch
+
+        public resource(): any {
+>resource : () => any
+
+            return undefined;
+>undefined : undefined
+        }
+    }
+
+type FileMatchOrMatch = FileMatch | Match;
+>FileMatchOrMatch : Match | FileMatch
+>FileMatch : FileMatch
+>Match : Match
+
+
+let elementA: FileMatchOrMatch, elementB: FileMatchOrMatch;
+>elementA : Match | FileMatch
+>FileMatchOrMatch : Match | FileMatch
+>elementB : Match | FileMatch
+>FileMatchOrMatch : Match | FileMatch
+
+if (elementA instanceof FileMatch && elementB instanceof FileMatch) {
+>elementA instanceof FileMatch && elementB instanceof FileMatch : boolean
+>elementA instanceof FileMatch : boolean
+>elementA : Match | FileMatch
+>FileMatch : typeof FileMatch
+>elementB instanceof FileMatch : boolean
+>elementB : Match | FileMatch
+>FileMatch : typeof FileMatch
+
+    let a = elementA.resource().path;
+>a : any
+>elementA.resource().path : any
+>elementA.resource() : any
+>elementA.resource : () => any
+>elementA : FileMatch
+>resource : () => any
+>path : any
+
+    let b = elementB.resource().path;
+>b : any
+>elementB.resource().path : any
+>elementB.resource() : any
+>elementB.resource : () => any
+>elementB : FileMatch
+>resource : () => any
+>path : any
+
+} else if (elementA instanceof Match && elementB instanceof Match) {
+>elementA instanceof Match && elementB instanceof Match : boolean
+>elementA instanceof Match : boolean
+>elementA : Match | FileMatch
+>Match : typeof Match
+>elementB instanceof Match : boolean
+>elementB : Match | FileMatch
+>Match : typeof Match
+
+    let a = elementA.range();
+>a : any
+>elementA.range() : any
+>elementA.range : () => any
+>elementA : Match
+>range : () => any
+
+    let b = elementB.range();
+>b : any
+>elementB.range() : any
+>elementB.range : () => any
+>elementB : Match
+>range : () => any
+}
+
diff --git a/tests/cases/compiler/narrowTypeByInstanceof.ts b/tests/cases/compiler/narrowTypeByInstanceof.ts
new file mode 100644
index 00000000000..6fe6693dd96
--- /dev/null
+++ b/tests/cases/compiler/narrowTypeByInstanceof.ts
@@ -0,0 +1,24 @@
+    class Match {
+        public range(): any {
+            return undefined;
+        }
+    }
+
+    class FileMatch {
+        public resource(): any {
+            return undefined;
+        }
+    }
+
+type FileMatchOrMatch = FileMatch | Match;
+
+
+let elementA: FileMatchOrMatch, elementB: FileMatchOrMatch;
+
+if (elementA instanceof FileMatch && elementB instanceof FileMatch) {
+    let a = elementA.resource().path;
+    let b = elementB.resource().path;
+} else if (elementA instanceof Match && elementB instanceof Match) {
+    let a = elementA.range();
+    let b = elementB.range();
+}