diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index 2fce851..0bcafd3 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -2573,8 +2573,9 @@
             bytearray.partition(sep)
 
    Split the sequence at the first occurrence of *sep*, and return a 3-tuple
-   containing the part before the separator, the separator, and the part
-   after the separator.  If the separator is not found, return a 3-tuple
+   containing the part before the separator, the separator itself or its
+   bytearray copy, and the part after the separator.
+   If the separator is not found, return a 3-tuple
    containing a copy of the original sequence, followed by two empty bytes or
    bytearray objects.
 
@@ -2629,8 +2630,9 @@
             bytearray.rpartition(sep)
 
    Split the sequence at the last occurrence of *sep*, and return a 3-tuple
-   containing the part before the separator, the separator, and the part
-   after the separator.  If the separator is not found, return a 3-tuple
+   containing the part before the separator, the separator itself or its
+   bytearray copy, and the part after the separator.
+   If the separator is not found, return a 3-tuple
    containing a copy of the original sequence, followed by two empty bytes or
    bytearray objects.
 
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 18091c1..1408fb4 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -548,8 +548,16 @@
         self.assertEqual(b.replace(b'i', b'a'), b'massassappa')
         self.assertEqual(b.replace(b'ss', b'x'), b'mixixippi')
 
+    def test_replace_int_error(self):
+        self.assertRaises(TypeError, self.type2test(b'a b').replace, 32, b'')
+
     def test_split_string_error(self):
         self.assertRaises(TypeError, self.type2test(b'a b').split, ' ')
+        self.assertRaises(TypeError, self.type2test(b'a b').rsplit, ' ')
+
+    def test_split_int_error(self):
+        self.assertRaises(TypeError, self.type2test(b'a b').split, 32)
+        self.assertRaises(TypeError, self.type2test(b'a b').rsplit, 32)
 
     def test_split_unicodewhitespace(self):
         for b in (b'a\x1Cb', b'a\x1Db', b'a\x1Eb', b'a\x1Fb'):
@@ -558,9 +566,6 @@
         b = self.type2test(b"\x09\x0A\x0B\x0C\x0D\x1C\x1D\x1E\x1F")
         self.assertEqual(b.split(), [b'\x1c\x1d\x1e\x1f'])
 
-    def test_rsplit_string_error(self):
-        self.assertRaises(TypeError, self.type2test(b'a b').rsplit, ' ')
-
     def test_rsplit_unicodewhitespace(self):
         b = self.type2test(b"\x09\x0A\x0B\x0C\x0D\x1C\x1D\x1E\x1F")
         self.assertEqual(b.rsplit(), [b'\x1c\x1d\x1e\x1f'])
@@ -576,6 +581,14 @@
         self.assertEqual(b.rpartition(b'i'), (b'mississipp', b'i', b''))
         self.assertEqual(b.rpartition(b'w'), (b'', b'', b'mississippi'))
 
+    def test_partition_string_error(self):
+        self.assertRaises(TypeError, self.type2test(b'a b').partition, ' ')
+        self.assertRaises(TypeError, self.type2test(b'a b').rpartition, ' ')
+
+    def test_partition_int_error(self):
+        self.assertRaises(TypeError, self.type2test(b'a b').partition, 32)
+        self.assertRaises(TypeError, self.type2test(b'a b').rpartition, 32)
+
     def test_pickling(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             for b in b"", b"a", b"abc", b"\xffab\x80", b"\0\0\377\0\0":
@@ -608,9 +621,14 @@
         self.assertEqual(self.type2test(b'abc').rstrip(memoryview(b'ac')), b'ab')
 
     def test_strip_string_error(self):
-        self.assertRaises(TypeError, self.type2test(b'abc').strip, 'b')
-        self.assertRaises(TypeError, self.type2test(b'abc').lstrip, 'b')
-        self.assertRaises(TypeError, self.type2test(b'abc').rstrip, 'b')
+        self.assertRaises(TypeError, self.type2test(b'abc').strip, 'ac')
+        self.assertRaises(TypeError, self.type2test(b'abc').lstrip, 'ac')
+        self.assertRaises(TypeError, self.type2test(b'abc').rstrip, 'ac')
+
+    def test_strip_int_error(self):
+        self.assertRaises(TypeError, self.type2test(b' abc ').strip, 32)
+        self.assertRaises(TypeError, self.type2test(b' abc ').lstrip, 32)
+        self.assertRaises(TypeError, self.type2test(b' abc ').rstrip, 32)
 
     def test_center(self):
         # Fill character can be either bytes or bytearray (issue 12380)
@@ -633,6 +651,11 @@
             self.assertEqual(b.rjust(7, fill_type(b'-')),
                              self.type2test(b'----abc'))
 
+    def test_xjust_int_error(self):
+        self.assertRaises(TypeError, self.type2test(b'abc').center, 7, 32)
+        self.assertRaises(TypeError, self.type2test(b'abc').ljust, 7, 32)
+        self.assertRaises(TypeError, self.type2test(b'abc').rjust, 7, 32)
+
     def test_ord(self):
         b = self.type2test(b'\0A\x7f\x80\xff')
         self.assertEqual([ord(b[i:i+1]) for i in range(len(b))],
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-10-28-19-11-05.bpo-20047.GuNAto.rst b/Misc/NEWS.d/next/Core and Builtins/2017-10-28-19-11-05.bpo-20047.GuNAto.rst
new file mode 100644
index 0000000..3594bac
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-10-28-19-11-05.bpo-20047.GuNAto.rst
@@ -0,0 +1,3 @@
+Bytearray methods partition() and rpartition() now accept only bytes-like
+objects as separator, as documented.  In particular they now raise TypeError
+rather of returning a bogus result when an integer is passed as a separator.
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 840d5b0..c92cfc0 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -104,6 +104,26 @@
                                         input, NULL);
 }
 
+static PyObject *
+_PyByteArray_FromBufferObject(PyObject *obj)
+{
+    PyObject *result;
+    Py_buffer view;
+
+    if (PyObject_GetBuffer(obj, &view, PyBUF_FULL_RO) < 0) {
+        return NULL;
+    }
+    result = PyByteArray_FromStringAndSize(NULL, view.len);
+    if (result != NULL &&
+        PyBuffer_ToContiguous(PyByteArray_AS_STRING(result),
+                              &view, view.len, 'C') < 0)
+    {
+        Py_CLEAR(result);
+    }
+    PyBuffer_Release(&view);
+    return result;
+}
+
 PyObject *
 PyByteArray_FromStringAndSize(const char *bytes, Py_ssize_t size)
 {
@@ -536,7 +556,8 @@
     if (values == (PyObject *)self) {
         /* Make a copy and call this function recursively */
         int err;
-        values = PyByteArray_FromObject(values);
+        values = PyByteArray_FromStringAndSize(PyByteArray_AS_STRING(values),
+                                               PyByteArray_GET_SIZE(values));
         if (values == NULL)
             return -1;
         err = bytearray_setslice(self, lo, hi, values);
@@ -1387,19 +1408,19 @@
 
 This will search for the separator sep in the bytearray. If the separator is
 found, returns a 3-tuple containing the part before the separator, the
-separator itself, and the part after it.
+separator itself, and the part after it as new bytearray objects.
 
-If the separator is not found, returns a 3-tuple containing the original
-bytearray object and two empty bytearray objects.
+If the separator is not found, returns a 3-tuple containing the copy of the
+original bytearray object and two empty bytearray objects.
 [clinic start generated code]*/
 
 static PyObject *
 bytearray_partition(PyByteArrayObject *self, PyObject *sep)
-/*[clinic end generated code: output=45d2525ddd35f957 input=86f89223892b70b5]*/
+/*[clinic end generated code: output=45d2525ddd35f957 input=8f644749ee4fc83a]*/
 {
     PyObject *bytesep, *result;
 
-    bytesep = PyByteArray_FromObject(sep);
+    bytesep = _PyByteArray_FromBufferObject(sep);
     if (! bytesep)
         return NULL;
 
@@ -1420,23 +1441,24 @@
     sep: object
     /
 
-Partition the bytes into three parts using the given separator.
+Partition the bytearray into three parts using the given separator.
 
-This will search for the separator sep in the bytearray, starting and the end.
+This will search for the separator sep in the bytearray, starting at the end.
 If the separator is found, returns a 3-tuple containing the part before the
-separator, the separator itself, and the part after it.
+separator, the separator itself, and the part after it as new bytearray
+objects.
 
 If the separator is not found, returns a 3-tuple containing two empty bytearray
-objects and the original bytearray object.
+objects and the copy of the original bytearray object.
 [clinic start generated code]*/
 
 static PyObject *
 bytearray_rpartition(PyByteArrayObject *self, PyObject *sep)
-/*[clinic end generated code: output=440de3c9426115e8 input=5f4094f2de87c8f3]*/
+/*[clinic end generated code: output=440de3c9426115e8 input=7e3df3e6cb8fa0ac]*/
 {
     PyObject *bytesep, *result;
 
-    bytesep = PyByteArray_FromObject(sep);
+    bytesep = _PyByteArray_FromBufferObject(sep);
     if (! bytesep)
         return NULL;
 
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 48b6501..7ba90aa 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -1834,7 +1834,7 @@
 
 Partition the bytes into three parts using the given separator.
 
-This will search for the separator sep in the bytes, starting and the end. If
+This will search for the separator sep in the bytes, starting at the end. If
 the separator is found, returns a 3-tuple containing the part before the
 separator, the separator itself, and the part after it.
 
@@ -1844,7 +1844,7 @@
 
 static PyObject *
 bytes_rpartition_impl(PyBytesObject *self, Py_buffer *sep)
-/*[clinic end generated code: output=191b114cbb028e50 input=67f689e63a62d478]*/
+/*[clinic end generated code: output=191b114cbb028e50 input=d78db010c8cfdbe1]*/
 {
     return stringlib_rpartition(
         (PyObject*) self,
diff --git a/Objects/clinic/bytearrayobject.c.h b/Objects/clinic/bytearrayobject.c.h
index 319c86e..d45592b 100644
--- a/Objects/clinic/bytearrayobject.c.h
+++ b/Objects/clinic/bytearrayobject.c.h
@@ -214,10 +214,10 @@
 "\n"
 "This will search for the separator sep in the bytearray. If the separator is\n"
 "found, returns a 3-tuple containing the part before the separator, the\n"
-"separator itself, and the part after it.\n"
+"separator itself, and the part after it as new bytearray objects.\n"
 "\n"
-"If the separator is not found, returns a 3-tuple containing the original\n"
-"bytearray object and two empty bytearray objects.");
+"If the separator is not found, returns a 3-tuple containing the copy of the\n"
+"original bytearray object and two empty bytearray objects.");
 
 #define BYTEARRAY_PARTITION_METHODDEF    \
     {"partition", (PyCFunction)bytearray_partition, METH_O, bytearray_partition__doc__},
@@ -226,14 +226,15 @@
 "rpartition($self, sep, /)\n"
 "--\n"
 "\n"
-"Partition the bytes into three parts using the given separator.\n"
+"Partition the bytearray into three parts using the given separator.\n"
 "\n"
-"This will search for the separator sep in the bytearray, starting and the end.\n"
+"This will search for the separator sep in the bytearray, starting at the end.\n"
 "If the separator is found, returns a 3-tuple containing the part before the\n"
-"separator, the separator itself, and the part after it.\n"
+"separator, the separator itself, and the part after it as new bytearray\n"
+"objects.\n"
 "\n"
 "If the separator is not found, returns a 3-tuple containing two empty bytearray\n"
-"objects and the original bytearray object.");
+"objects and the copy of the original bytearray object.");
 
 #define BYTEARRAY_RPARTITION_METHODDEF    \
     {"rpartition", (PyCFunction)bytearray_rpartition, METH_O, bytearray_rpartition__doc__},
@@ -711,4 +712,4 @@
 {
     return bytearray_sizeof_impl(self);
 }
-/*[clinic end generated code: output=e53f10084457a46b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c2804d009182328c input=a9049054013a1b77]*/
diff --git a/Objects/clinic/bytesobject.c.h b/Objects/clinic/bytesobject.c.h
index 315f6f2..9c358b5 100644
--- a/Objects/clinic/bytesobject.c.h
+++ b/Objects/clinic/bytesobject.c.h
@@ -86,7 +86,7 @@
 "\n"
 "Partition the bytes into three parts using the given separator.\n"
 "\n"
-"This will search for the separator sep in the bytes, starting and the end. If\n"
+"This will search for the separator sep in the bytes, starting at the end. If\n"
 "the separator is found, returns a 3-tuple containing the part before the\n"
 "separator, the separator itself, and the part after it.\n"
 "\n"
@@ -499,4 +499,4 @@
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=9e3374bd7d04c163 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=fc9e02359cc56d36 input=a9049054013a1b77]*/
diff --git a/Objects/clinic/unicodeobject.c.h b/Objects/clinic/unicodeobject.c.h
index ca90e6d..0936527 100644
--- a/Objects/clinic/unicodeobject.c.h
+++ b/Objects/clinic/unicodeobject.c.h
@@ -682,7 +682,7 @@
 "\n"
 "Partition the string into three parts using the given separator.\n"
 "\n"
-"This will search for the separator in the string, starting and the end. If\n"
+"This will search for the separator in the string, starting at the end. If\n"
 "the separator is found, returns a 3-tuple containing the part before the\n"
 "separator, the separator itself, and the part after it.\n"
 "\n"
@@ -930,4 +930,4 @@
 {
     return unicode_sizeof_impl(self);
 }
-/*[clinic end generated code: output=8fd799fd7f2cc724 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=816292e81a8a732e input=a9049054013a1b77]*/
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 2f30877..6533f41 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -13067,7 +13067,7 @@
 
 Partition the string into three parts using the given separator.
 
-This will search for the separator in the string, starting and the end. If
+This will search for the separator in the string, starting at the end. If
 the separator is found, returns a 3-tuple containing the part before the
 separator, the separator itself, and the part after it.
 
@@ -13077,7 +13077,7 @@
 
 static PyObject *
 unicode_rpartition(PyObject *self, PyObject *sep)
-/*[clinic end generated code: output=1aa13cf1156572aa input=e77c7acb69bdfca6]*/
+/*[clinic end generated code: output=1aa13cf1156572aa input=c4b7db3ef5cf336a]*/
 {
     return PyUnicode_RPartition(self, sep);
 }