diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index 1ac5397e0..85fa0b120 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -575,7 +575,9 @@ if sys.version_info >= (3,):
         def endswith(self, suffix: Union[bytes, Tuple[bytes, ...]]) -> bool: ...
         def expandtabs(self, tabsize: int = ...) -> bytes: ...
         def find(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
-        if sys.version_info >= (3, 5):
+        if sys.version_info >= (3, 8):
+            def hex(self, sep: Union[str, bytes] = ..., bytes_per_sep: int = ...) -> str: ...
+        elif sys.version_info >= (3, 5):
             def hex(self) -> str: ...
         def index(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
         def isalnum(self) -> bool: ...
@@ -819,8 +821,13 @@ class memoryview(Sized, Container[_mv_container_type]):
     @overload
     def __setitem__(self, s: slice, o: Sequence[bytes]) -> None: ...
 
-    def tobytes(self) -> bytes: ...
+    if sys.version_info >= (3, 8):
+        def tobytes(self, order: Optional[Literal["C", "F", "A"]] = ...) -> bytes: ...
+    else:
+        def tobytes(self) -> bytes: ...
     def tolist(self) -> List[int]: ...
+    if sys.version_info >= (3, 8):
+        def toreadonly(self) -> memoryview: ...
 
     if sys.version_info >= (3, 2):
         def release(self) -> None: ...
diff --git a/stdlib/2and3/builtins.pyi b/stdlib/2and3/builtins.pyi
index 1ac5397e0..85fa0b120 100644
--- a/stdlib/2and3/builtins.pyi
+++ b/stdlib/2and3/builtins.pyi
@@ -575,7 +575,9 @@ if sys.version_info >= (3,):
         def endswith(self, suffix: Union[bytes, Tuple[bytes, ...]]) -> bool: ...
         def expandtabs(self, tabsize: int = ...) -> bytes: ...
         def find(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
-        if sys.version_info >= (3, 5):
+        if sys.version_info >= (3, 8):
+            def hex(self, sep: Union[str, bytes] = ..., bytes_per_sep: int = ...) -> str: ...
+        elif sys.version_info >= (3, 5):
             def hex(self) -> str: ...
         def index(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
         def isalnum(self) -> bool: ...
@@ -819,8 +821,13 @@ class memoryview(Sized, Container[_mv_container_type]):
     @overload
     def __setitem__(self, s: slice, o: Sequence[bytes]) -> None: ...
 
-    def tobytes(self) -> bytes: ...
+    if sys.version_info >= (3, 8):
+        def tobytes(self, order: Optional[Literal["C", "F", "A"]] = ...) -> bytes: ...
+    else:
+        def tobytes(self) -> bytes: ...
     def tolist(self) -> List[int]: ...
+    if sys.version_info >= (3, 8):
+        def toreadonly(self) -> memoryview: ...
 
     if sys.version_info >= (3, 2):
         def release(self) -> None: ...