diff --git a/Doc/library/ensurepip.rst b/Doc/library/ensurepip.rst
index a2bb045e57e..c5e27388198 100644
--- a/Doc/library/ensurepip.rst
+++ b/Doc/library/ensurepip.rst
@@ -56,8 +56,9 @@ is at least as recent as the one bundled with ``ensurepip``, pass the
 By default, ``pip`` is installed into the current virtual environment
 (if one is active) or into the system site packages (if there is no
 active virtual environment). The installation location can be controlled
-through two additional command line options:
+through some additional command line options:
 
+* ``--prefix <dir>``: Installs ``pip`` using the given directory prefix.
 * ``--root <dir>``: Installs ``pip`` relative to the given root directory
   rather than the root of the currently active virtual environment (if any)
   or the default root for the current Python installation.
@@ -89,7 +90,7 @@ Module API
    Returns a string specifying the bundled version of pip that will be
    installed when bootstrapping an environment.
 
-.. function:: bootstrap(root=None, upgrade=False, user=False, \
+.. function:: bootstrap(root=None, prefix=None, upgrade=False, user=False, \
                         altinstall=False, default_pip=False, \
                         verbosity=0)
 
@@ -99,6 +100,8 @@ Module API
    If *root* is ``None``, then installation uses the default install location
    for the current environment.
 
+   *prefix* specifies the directory prefix to use when installing.
+
    *upgrade* indicates whether or not to upgrade an existing installation
    of an earlier version of ``pip`` to the bundled version.
 
@@ -119,6 +122,8 @@ Module API
    *verbosity* controls the level of output to :data:`sys.stdout` from the
    bootstrapping operation.
 
+   .. versionchanged:: 3.9 the *prefix* parameter was added.
+
    .. audit-event:: ensurepip.bootstrap root ensurepip.bootstrap
 
    .. note::
diff --git a/Lib/ensurepip/__init__.py b/Lib/ensurepip/__init__.py
index 386ed6c25c7..e4293e32860 100644
--- a/Lib/ensurepip/__init__.py
+++ b/Lib/ensurepip/__init__.py
@@ -49,27 +49,27 @@ def _disable_pip_configuration_settings():
     os.environ['PIP_CONFIG_FILE'] = os.devnull
 
 
-def bootstrap(*, root=None, upgrade=False, user=False,
+def bootstrap(*, root=None, prefix=None, upgrade=False, user=False,
               altinstall=False, default_pip=False,
               verbosity=0):
     """
     Bootstrap pip into the current Python installation (or the given root
-    directory).
+    and directory prefix).
 
     Note that calling this function will alter both sys.path and os.environ.
     """
     # Discard the return value
-    _bootstrap(root=root, upgrade=upgrade, user=user,
+    _bootstrap(root=root, prefix=prefix, upgrade=upgrade, user=user,
                altinstall=altinstall, default_pip=default_pip,
                verbosity=verbosity)
 
 
-def _bootstrap(*, root=None, upgrade=False, user=False,
+def _bootstrap(*, root=None, prefix=None, upgrade=False, user=False,
               altinstall=False, default_pip=False,
               verbosity=0):
     """
     Bootstrap pip into the current Python installation (or the given root
-    directory). Returns pip command status code.
+    and directory prefix). Returns pip command status code.
 
     Note that calling this function will alter both sys.path and os.environ.
     """
@@ -112,6 +112,8 @@ def _bootstrap(*, root=None, upgrade=False, user=False,
         args = ["install", "--no-index", "--find-links", tmpdir]
         if root:
             args += ["--root", root]
+        if prefix:
+            args += ["--prefix", prefix]
         if upgrade:
             args += ["--upgrade"]
         if user:
@@ -183,6 +185,11 @@ def _main(argv=None):
         default=None,
         help="Install everything relative to this alternate root directory.",
     )
+    parser.add_argument(
+        "--prefix",
+        default=None,
+        help="Install everything using this prefix.",
+    )
     parser.add_argument(
         "--altinstall",
         action="store_true",
@@ -202,6 +209,7 @@ def _main(argv=None):
 
     return _bootstrap(
         root=args.root,
+        prefix=args.prefix,
         upgrade=args.upgrade,
         user=args.user,
         verbosity=args.verbosity,
diff --git a/Lib/test/test_ensurepip.py b/Lib/test/test_ensurepip.py
index 89966893092..79de02c574c 100644
--- a/Lib/test/test_ensurepip.py
+++ b/Lib/test/test_ensurepip.py
@@ -61,6 +61,17 @@ class TestBootstrap(EnsurepipMixin, unittest.TestCase):
             unittest.mock.ANY,
         )
 
+    def test_bootstrapping_with_prefix(self):
+        ensurepip.bootstrap(prefix="/foo/bar/")
+        self.run_pip.assert_called_once_with(
+            [
+                "install", "--no-index", "--find-links",
+                unittest.mock.ANY, "--prefix", "/foo/bar/",
+                "setuptools", "pip",
+            ],
+            unittest.mock.ANY,
+        )
+
     def test_bootstrapping_with_user(self):
         ensurepip.bootstrap(user=True)
 
diff --git a/Makefile.pre.in b/Makefile.pre.in
index d08c78df394..532ce59ff9d 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1181,7 +1181,7 @@ install: @FRAMEWORKINSTALLFIRST@ commoninstall bininstall maninstall @FRAMEWORKI
 			install|*) ensurepip="" ;; \
 		esac; \
 		$(RUNSHARED) $(PYTHON_FOR_BUILD) -m ensurepip \
-			$$ensurepip --root=$(DESTDIR)/ ; \
+			$$ensurepip --root=$(DESTDIR)/ --prefix=$(prefix) ; \
 	fi
 
 altinstall: commoninstall
@@ -1191,7 +1191,7 @@ altinstall: commoninstall
 			install|*) ensurepip="--altinstall" ;; \
 		esac; \
 		$(RUNSHARED) $(PYTHON_FOR_BUILD) -m ensurepip \
-			$$ensurepip --root=$(DESTDIR)/ ; \
+			$$ensurepip --root=$(DESTDIR)/ --prefix=$(prefix) ; \
 	fi
 
 commoninstall:  check-clean-src @FRAMEWORKALTINSTALLFIRST@ \
diff --git a/Misc/NEWS.d/next/Build/2019-12-16-17-50-42.bpo-31046.XA-Qfr.rst b/Misc/NEWS.d/next/Build/2019-12-16-17-50-42.bpo-31046.XA-Qfr.rst
new file mode 100644
index 00000000000..07eb89d4d23
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2019-12-16-17-50-42.bpo-31046.XA-Qfr.rst
@@ -0,0 +1 @@
+A directory prefix can now be specified when using :mod:`ensurepip`.