diff --git a/src/lib/es2018.asyncgenerator.d.ts b/src/lib/es2018.asyncgenerator.d.ts
index 76275c92575c0..7080d427d41b8 100644
--- a/src/lib/es2018.asyncgenerator.d.ts
+++ b/src/lib/es2018.asyncgenerator.d.ts
@@ -2,9 +2,9 @@
 
 interface AsyncGenerator<T = unknown, TReturn = any, TNext = unknown> extends AsyncIterator<T, TReturn, TNext> {
     // NOTE: 'next' is defined using a tuple to ensure we report the correct assignability errors in all places.
-    next(...args: [] | [TNext | PromiseLike<TNext>]): Promise<IteratorResult<T, TReturn>>;
-    return(value: TReturn | PromiseLike<TReturn>): Promise<IteratorResult<T, TReturn>>;
-    throw(e: any): Promise<IteratorResult<T, TReturn>>;
+    next(...args: [] | [TNext]): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
+    return(value: TReturn): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
+    throw(e: any): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
     [Symbol.asyncIterator](): AsyncGenerator<T, TReturn, TNext>;
 }
 
diff --git a/src/lib/es2018.asynciterable.d.ts b/src/lib/es2018.asynciterable.d.ts
index d5d83f31893bb..8465b30fbea84 100644
--- a/src/lib/es2018.asynciterable.d.ts
+++ b/src/lib/es2018.asynciterable.d.ts
@@ -11,9 +11,9 @@ interface SymbolConstructor {
 
 interface AsyncIterator<T, TReturn = any, TNext = undefined> {
     // NOTE: 'next' is defined using a tuple to ensure we report the correct assignability errors in all places.
-    next(...args: [] | [TNext | PromiseLike<TNext>]): Promise<IteratorResult<T, TReturn>>;
-    return?(value?: TReturn | PromiseLike<TReturn>): Promise<IteratorResult<T, TReturn>>;
-    throw?(e?: any): Promise<IteratorResult<T, TReturn>>;
+    next(...args: [] | [TNext]): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
+    return?(value?: TReturn): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
+    throw?(e?: any): Promise<IteratorResult<T, TReturn extends PromiseLike<infer UReturn> ? UReturn : TReturn>>;
 }
 
 interface AsyncIterable<T> {
@@ -22,4 +22,4 @@ interface AsyncIterable<T> {
 
 interface AsyncIterableIterator<T> extends AsyncIterator<T> {
     [Symbol.asyncIterator](): AsyncIterableIterator<T>;
-}
\ No newline at end of file
+}
diff --git a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
index d7ec011bcedc1..9f22060b9e936 100644
--- a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
+++ b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(10,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterableIterator<number>'.
     Types of property 'next' are incompatible.
-      Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+      Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
           Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
@@ -14,7 +14,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(16,7): error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterableIterator<number>'.
   Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterableIterator<number>'.
     Types of property 'next' are incompatible.
-      Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+      Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(19,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterable<number>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterable<number>'.
@@ -22,7 +22,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
       Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
         Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
           Types of property 'next' are incompatible.
-            Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+            Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(22,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterable<number>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterable<number>'.
@@ -32,7 +32,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
       Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
         Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
           Types of property 'next' are incompatible.
-            Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+            Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(28,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
@@ -53,7 +53,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(67,42): error TS2741: Property '[Symbol.iterator]' is missing in type 'AsyncGenerator<any, any, any>' but required in type 'Iterable<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(70,42): error TS2322: Type 'AsyncGenerator<number, any, undefined>' is not assignable to type 'Iterator<number, any, undefined>'.
   Types of property 'next' are incompatible.
-    Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
+    Type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
       Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
         Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(74,12): error TS2504: Type '{}' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
@@ -79,7 +79,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 !!! error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
 !!! error TS2322:   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterableIterator<number>'.
 !!! error TS2322:     Types of property 'next' are incompatible.
-!!! error TS2322:       Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+!!! error TS2322:       Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
 !!! error TS2322:         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 !!! error TS2322:           Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
 !!! error TS2322:             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
@@ -98,7 +98,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 !!! error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterableIterator<number>'.
 !!! error TS2322:   Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterableIterator<number>'.
 !!! error TS2322:     Types of property 'next' are incompatible.
-!!! error TS2322:       Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+!!! error TS2322:       Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
 !!! error TS2322:         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield* (async function * () { yield "a"; })();
     };
@@ -110,7 +110,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 !!! error TS2322:       Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
 !!! error TS2322:         Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
 !!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+!!! error TS2322:             Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
 !!! error TS2322:               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield "a";
     };
@@ -128,7 +128,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 !!! error TS2322:       Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
 !!! error TS2322:         Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
 !!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>'.
+!!! error TS2322:             Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
 !!! error TS2322:               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield* (async function * () { yield "a"; })();
     };
@@ -211,7 +211,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
                                              ~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'AsyncGenerator<number, any, undefined>' is not assignable to type 'Iterator<number, any, undefined>'.
 !!! error TS2322:   Types of property 'next' are incompatible.
-!!! error TS2322:     Type '(...args: [] | [PromiseLike<undefined>]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
+!!! error TS2322:     Type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
 !!! error TS2322:       Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
 !!! error TS2322:         Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
 !!! related TS2728 /.ts/lib.es2015.iterable.d.ts:33:5: 'value' is declared here.