diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a24a8518618..e3dbc1b0efc 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -12124,7 +12124,8 @@ namespace ts {
                         }
                     }
                 }
-                return getIntersectionType(constraints);
+                // The source types were normalized; ensure the result is normalized too.
+                return getNormalizedType(getIntersectionType(constraints), /*writing*/ false);
             }
             return undefined;
         }
diff --git a/tests/baselines/reference/instanceofTypeAliasToGenericClass.js b/tests/baselines/reference/instanceofTypeAliasToGenericClass.js
new file mode 100644
index 00000000000..4a8257f781c
--- /dev/null
+++ b/tests/baselines/reference/instanceofTypeAliasToGenericClass.js
@@ -0,0 +1,29 @@
+//// [instanceofTypeAliasToGenericClass.ts]
+declare class TableClass<S = any> {
+    _field: S;
+}
+
+export type Table = TableClass;
+
+function fn<T extends Table>(o: T) {
+    return o instanceof TableClass;
+}
+
+function fn2<T extends TableClass>(o: T) {
+    return o instanceof TableClass;
+}
+
+declare const o: Table;
+o instanceof TableClass;
+
+
+//// [instanceofTypeAliasToGenericClass.js]
+"use strict";
+exports.__esModule = true;
+function fn(o) {
+    return o instanceof TableClass;
+}
+function fn2(o) {
+    return o instanceof TableClass;
+}
+o instanceof TableClass;
diff --git a/tests/baselines/reference/instanceofTypeAliasToGenericClass.symbols b/tests/baselines/reference/instanceofTypeAliasToGenericClass.symbols
new file mode 100644
index 00000000000..2c834f99ffa
--- /dev/null
+++ b/tests/baselines/reference/instanceofTypeAliasToGenericClass.symbols
@@ -0,0 +1,46 @@
+=== tests/cases/compiler/instanceofTypeAliasToGenericClass.ts ===
+declare class TableClass<S = any> {
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+>S : Symbol(S, Decl(instanceofTypeAliasToGenericClass.ts, 0, 25))
+
+    _field: S;
+>_field : Symbol(TableClass._field, Decl(instanceofTypeAliasToGenericClass.ts, 0, 35))
+>S : Symbol(S, Decl(instanceofTypeAliasToGenericClass.ts, 0, 25))
+}
+
+export type Table = TableClass;
+>Table : Symbol(Table, Decl(instanceofTypeAliasToGenericClass.ts, 2, 1))
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+
+function fn<T extends Table>(o: T) {
+>fn : Symbol(fn, Decl(instanceofTypeAliasToGenericClass.ts, 4, 31))
+>T : Symbol(T, Decl(instanceofTypeAliasToGenericClass.ts, 6, 12))
+>Table : Symbol(Table, Decl(instanceofTypeAliasToGenericClass.ts, 2, 1))
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 6, 29))
+>T : Symbol(T, Decl(instanceofTypeAliasToGenericClass.ts, 6, 12))
+
+    return o instanceof TableClass;
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 6, 29))
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+}
+
+function fn2<T extends TableClass>(o: T) {
+>fn2 : Symbol(fn2, Decl(instanceofTypeAliasToGenericClass.ts, 8, 1))
+>T : Symbol(T, Decl(instanceofTypeAliasToGenericClass.ts, 10, 13))
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 10, 35))
+>T : Symbol(T, Decl(instanceofTypeAliasToGenericClass.ts, 10, 13))
+
+    return o instanceof TableClass;
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 10, 35))
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+}
+
+declare const o: Table;
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 14, 13))
+>Table : Symbol(Table, Decl(instanceofTypeAliasToGenericClass.ts, 2, 1))
+
+o instanceof TableClass;
+>o : Symbol(o, Decl(instanceofTypeAliasToGenericClass.ts, 14, 13))
+>TableClass : Symbol(TableClass, Decl(instanceofTypeAliasToGenericClass.ts, 0, 0))
+
diff --git a/tests/baselines/reference/instanceofTypeAliasToGenericClass.types b/tests/baselines/reference/instanceofTypeAliasToGenericClass.types
new file mode 100644
index 00000000000..8a487e386b0
--- /dev/null
+++ b/tests/baselines/reference/instanceofTypeAliasToGenericClass.types
@@ -0,0 +1,39 @@
+=== tests/cases/compiler/instanceofTypeAliasToGenericClass.ts ===
+declare class TableClass<S = any> {
+>TableClass : TableClass<S>
+
+    _field: S;
+>_field : S
+}
+
+export type Table = TableClass;
+>Table : TableClass<any>
+
+function fn<T extends Table>(o: T) {
+>fn : <T extends Table>(o: T) => boolean
+>o : T
+
+    return o instanceof TableClass;
+>o instanceof TableClass : boolean
+>o : T
+>TableClass : typeof TableClass
+}
+
+function fn2<T extends TableClass>(o: T) {
+>fn2 : <T extends TableClass<any>>(o: T) => boolean
+>o : T
+
+    return o instanceof TableClass;
+>o instanceof TableClass : boolean
+>o : T
+>TableClass : typeof TableClass
+}
+
+declare const o: Table;
+>o : Table
+
+o instanceof TableClass;
+>o instanceof TableClass : boolean
+>o : Table
+>TableClass : typeof TableClass
+
diff --git a/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.errors.txt b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.errors.txt
new file mode 100644
index 00000000000..e137085073a
--- /dev/null
+++ b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.errors.txt
@@ -0,0 +1,94 @@
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(21,5): error TS2322: Type 'T' is not assignable to type 'boolean'.
+  Type 'TableClass<any>' is not assignable to type 'boolean'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(22,5): error TS2322: Type 'T' is not assignable to type 'string | number'.
+  Type 'TableClass<any>' is not assignable to type 'string | number'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(23,5): error TS2322: Type 'T' is not assignable to type 'string | Something'.
+  Type 'TableClass<any>' is not assignable to type 'string | Something'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(24,5): error TS2322: Type 'T' is not assignable to type 'Something | SomethingElse'.
+  Type 'TableClass<any>' is not assignable to type 'Something | SomethingElse'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(28,5): error TS2322: Type 'T' is not assignable to type 'boolean'.
+  Type 'TableClass<any>' is not assignable to type 'boolean'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(29,5): error TS2322: Type 'T' is not assignable to type 'string | number'.
+  Type 'TableClass<any>' is not assignable to type 'string | number'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(30,5): error TS2322: Type 'T' is not assignable to type 'string | Something'.
+  Type 'TableClass<any>' is not assignable to type 'string | Something'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(31,5): error TS2322: Type 'T' is not assignable to type 'Something | SomethingElse'.
+  Type 'TableClass<any>' is not assignable to type 'Something | SomethingElse'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(35,1): error TS2322: Type 'Table' is not assignable to type 'boolean'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(36,1): error TS2322: Type 'Table' is not assignable to type 'string | number'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(37,1): error TS2322: Type 'Table' is not assignable to type 'string | Something'.
+tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts(38,1): error TS2322: Type 'Table' is not assignable to type 'Something | SomethingElse'.
+
+
+==== tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts (12 errors) ====
+    declare class TableClass<S = any> {
+        _field: S;
+    }
+    
+    export type Table = TableClass;
+    
+    interface Something {
+        prop: number;
+    }
+    
+    interface SomethingElse {
+        prop2: string;
+    }
+    
+    declare let aBoolean: boolean;
+    declare let aStringOrNumber: string | number;
+    declare let aStringOrSomething: string | Something;
+    declare let someUnion: Something | SomethingElse;
+    
+    function fn<T extends Table>(o: T) {
+        aBoolean = o;
+        ~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'boolean'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'boolean'.
+        aStringOrNumber = o;
+        ~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'string | number'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'string | number'.
+        aStringOrSomething = o;
+        ~~~~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'string | Something'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'string | Something'.
+        someUnion = o;
+        ~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'Something | SomethingElse'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'Something | SomethingElse'.
+    }
+    
+    function fn2<T extends TableClass>(o: T) {
+        aBoolean = o;
+        ~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'boolean'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'boolean'.
+        aStringOrNumber = o;
+        ~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'string | number'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'string | number'.
+        aStringOrSomething = o;
+        ~~~~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'string | Something'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'string | Something'.
+        someUnion = o;
+        ~~~~~~~~~
+!!! error TS2322: Type 'T' is not assignable to type 'Something | SomethingElse'.
+!!! error TS2322:   Type 'TableClass<any>' is not assignable to type 'Something | SomethingElse'.
+    }
+    
+    declare const o: Table;
+    aBoolean = o;
+    ~~~~~~~~
+!!! error TS2322: Type 'Table' is not assignable to type 'boolean'.
+    aStringOrNumber = o;
+    ~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'Table' is not assignable to type 'string | number'.
+    aStringOrSomething = o;
+    ~~~~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'Table' is not assignable to type 'string | Something'.
+    someUnion = o;
+    ~~~~~~~~~
+!!! error TS2322: Type 'Table' is not assignable to type 'Something | SomethingElse'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.js b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.js
new file mode 100644
index 00000000000..6384bfa3ce4
--- /dev/null
+++ b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.js
@@ -0,0 +1,60 @@
+//// [typeVariableConstraintedToAliasNotAssignableToUnion.ts]
+declare class TableClass<S = any> {
+    _field: S;
+}
+
+export type Table = TableClass;
+
+interface Something {
+    prop: number;
+}
+
+interface SomethingElse {
+    prop2: string;
+}
+
+declare let aBoolean: boolean;
+declare let aStringOrNumber: string | number;
+declare let aStringOrSomething: string | Something;
+declare let someUnion: Something | SomethingElse;
+
+function fn<T extends Table>(o: T) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+
+function fn2<T extends TableClass>(o: T) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+
+declare const o: Table;
+aBoolean = o;
+aStringOrNumber = o;
+aStringOrSomething = o;
+someUnion = o;
+
+
+//// [typeVariableConstraintedToAliasNotAssignableToUnion.js]
+"use strict";
+exports.__esModule = true;
+function fn(o) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+function fn2(o) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+aBoolean = o;
+aStringOrNumber = o;
+aStringOrSomething = o;
+someUnion = o;
diff --git a/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.symbols b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.symbols
new file mode 100644
index 00000000000..bb13e96ad7e
--- /dev/null
+++ b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.symbols
@@ -0,0 +1,111 @@
+=== tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts ===
+declare class TableClass<S = any> {
+>TableClass : Symbol(TableClass, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 0))
+>S : Symbol(S, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 25))
+
+    _field: S;
+>_field : Symbol(TableClass._field, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 35))
+>S : Symbol(S, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 25))
+}
+
+export type Table = TableClass;
+>Table : Symbol(Table, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 2, 1))
+>TableClass : Symbol(TableClass, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 0))
+
+interface Something {
+>Something : Symbol(Something, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 4, 31))
+
+    prop: number;
+>prop : Symbol(Something.prop, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 6, 21))
+}
+
+interface SomethingElse {
+>SomethingElse : Symbol(SomethingElse, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 8, 1))
+
+    prop2: string;
+>prop2 : Symbol(SomethingElse.prop2, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 10, 25))
+}
+
+declare let aBoolean: boolean;
+>aBoolean : Symbol(aBoolean, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 14, 11))
+
+declare let aStringOrNumber: string | number;
+>aStringOrNumber : Symbol(aStringOrNumber, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 15, 11))
+
+declare let aStringOrSomething: string | Something;
+>aStringOrSomething : Symbol(aStringOrSomething, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 16, 11))
+>Something : Symbol(Something, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 4, 31))
+
+declare let someUnion: Something | SomethingElse;
+>someUnion : Symbol(someUnion, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 17, 11))
+>Something : Symbol(Something, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 4, 31))
+>SomethingElse : Symbol(SomethingElse, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 8, 1))
+
+function fn<T extends Table>(o: T) {
+>fn : Symbol(fn, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 17, 49))
+>T : Symbol(T, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 12))
+>Table : Symbol(Table, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 2, 1))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 29))
+>T : Symbol(T, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 12))
+
+    aBoolean = o;
+>aBoolean : Symbol(aBoolean, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 14, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 29))
+
+    aStringOrNumber = o;
+>aStringOrNumber : Symbol(aStringOrNumber, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 15, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 29))
+
+    aStringOrSomething = o;
+>aStringOrSomething : Symbol(aStringOrSomething, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 16, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 29))
+
+    someUnion = o;
+>someUnion : Symbol(someUnion, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 17, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 19, 29))
+}
+
+function fn2<T extends TableClass>(o: T) {
+>fn2 : Symbol(fn2, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 24, 1))
+>T : Symbol(T, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 13))
+>TableClass : Symbol(TableClass, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 0, 0))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 35))
+>T : Symbol(T, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 13))
+
+    aBoolean = o;
+>aBoolean : Symbol(aBoolean, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 14, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 35))
+
+    aStringOrNumber = o;
+>aStringOrNumber : Symbol(aStringOrNumber, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 15, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 35))
+
+    aStringOrSomething = o;
+>aStringOrSomething : Symbol(aStringOrSomething, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 16, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 35))
+
+    someUnion = o;
+>someUnion : Symbol(someUnion, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 17, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 26, 35))
+}
+
+declare const o: Table;
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 33, 13))
+>Table : Symbol(Table, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 2, 1))
+
+aBoolean = o;
+>aBoolean : Symbol(aBoolean, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 14, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 33, 13))
+
+aStringOrNumber = o;
+>aStringOrNumber : Symbol(aStringOrNumber, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 15, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 33, 13))
+
+aStringOrSomething = o;
+>aStringOrSomething : Symbol(aStringOrSomething, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 16, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 33, 13))
+
+someUnion = o;
+>someUnion : Symbol(someUnion, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 17, 11))
+>o : Symbol(o, Decl(typeVariableConstraintedToAliasNotAssignableToUnion.ts, 33, 13))
+
diff --git a/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.types b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.types
new file mode 100644
index 00000000000..899df75a152
--- /dev/null
+++ b/tests/baselines/reference/typeVariableConstraintedToAliasNotAssignableToUnion.types
@@ -0,0 +1,106 @@
+=== tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts ===
+declare class TableClass<S = any> {
+>TableClass : TableClass<S>
+
+    _field: S;
+>_field : S
+}
+
+export type Table = TableClass;
+>Table : TableClass<any>
+
+interface Something {
+    prop: number;
+>prop : number
+}
+
+interface SomethingElse {
+    prop2: string;
+>prop2 : string
+}
+
+declare let aBoolean: boolean;
+>aBoolean : boolean
+
+declare let aStringOrNumber: string | number;
+>aStringOrNumber : string | number
+
+declare let aStringOrSomething: string | Something;
+>aStringOrSomething : string | Something
+
+declare let someUnion: Something | SomethingElse;
+>someUnion : Something | SomethingElse
+
+function fn<T extends Table>(o: T) {
+>fn : <T extends Table>(o: T) => void
+>o : T
+
+    aBoolean = o;
+>aBoolean = o : T
+>aBoolean : boolean
+>o : T
+
+    aStringOrNumber = o;
+>aStringOrNumber = o : T
+>aStringOrNumber : string | number
+>o : T
+
+    aStringOrSomething = o;
+>aStringOrSomething = o : T
+>aStringOrSomething : string | Something
+>o : T
+
+    someUnion = o;
+>someUnion = o : T
+>someUnion : Something | SomethingElse
+>o : T
+}
+
+function fn2<T extends TableClass>(o: T) {
+>fn2 : <T extends TableClass<any>>(o: T) => void
+>o : T
+
+    aBoolean = o;
+>aBoolean = o : T
+>aBoolean : boolean
+>o : T
+
+    aStringOrNumber = o;
+>aStringOrNumber = o : T
+>aStringOrNumber : string | number
+>o : T
+
+    aStringOrSomething = o;
+>aStringOrSomething = o : T
+>aStringOrSomething : string | Something
+>o : T
+
+    someUnion = o;
+>someUnion = o : T
+>someUnion : Something | SomethingElse
+>o : T
+}
+
+declare const o: Table;
+>o : Table
+
+aBoolean = o;
+>aBoolean = o : Table
+>aBoolean : boolean
+>o : Table
+
+aStringOrNumber = o;
+>aStringOrNumber = o : Table
+>aStringOrNumber : string | number
+>o : Table
+
+aStringOrSomething = o;
+>aStringOrSomething = o : Table
+>aStringOrSomething : string | Something
+>o : Table
+
+someUnion = o;
+>someUnion = o : Table
+>someUnion : Something | SomethingElse
+>o : Table
+
diff --git a/tests/cases/compiler/instanceofTypeAliasToGenericClass.ts b/tests/cases/compiler/instanceofTypeAliasToGenericClass.ts
new file mode 100644
index 00000000000..6c9b4499778
--- /dev/null
+++ b/tests/cases/compiler/instanceofTypeAliasToGenericClass.ts
@@ -0,0 +1,16 @@
+declare class TableClass<S = any> {
+    _field: S;
+}
+
+export type Table = TableClass;
+
+function fn<T extends Table>(o: T) {
+    return o instanceof TableClass;
+}
+
+function fn2<T extends TableClass>(o: T) {
+    return o instanceof TableClass;
+}
+
+declare const o: Table;
+o instanceof TableClass;
diff --git a/tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts b/tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts
new file mode 100644
index 00000000000..89416ee1a27
--- /dev/null
+++ b/tests/cases/compiler/typeVariableConstraintedToAliasNotAssignableToUnion.ts
@@ -0,0 +1,38 @@
+declare class TableClass<S = any> {
+    _field: S;
+}
+
+export type Table = TableClass;
+
+interface Something {
+    prop: number;
+}
+
+interface SomethingElse {
+    prop2: string;
+}
+
+declare let aBoolean: boolean;
+declare let aStringOrNumber: string | number;
+declare let aStringOrSomething: string | Something;
+declare let someUnion: Something | SomethingElse;
+
+function fn<T extends Table>(o: T) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+
+function fn2<T extends TableClass>(o: T) {
+    aBoolean = o;
+    aStringOrNumber = o;
+    aStringOrSomething = o;
+    someUnion = o;
+}
+
+declare const o: Table;
+aBoolean = o;
+aStringOrNumber = o;
+aStringOrSomething = o;
+someUnion = o;