diff --git a/piptools/repositories/local.py b/piptools/repositories/local.py
index b2356d811..6c91d1b4f 100644
--- a/piptools/repositories/local.py
+++ b/piptools/repositories/local.py
@@ -33,7 +33,8 @@ class LocalRequirementsRepository(BaseRepository):
     PyPI.  This keeps updates to the requirements.txt down to a minimum.
     """
 
-    def __init__(self, existing_pins, proxied_repository):
+    def __init__(self, existing_pins, proxied_repository, reuse_hashes=True):
+        self._reuse_hashes = reuse_hashes
         self.repository = proxied_repository
         self.existing_pins = existing_pins
 
@@ -74,8 +75,9 @@ def get_dependencies(self, ireq):
         return self.repository.get_dependencies(ireq)
 
     def get_hashes(self, ireq):
-        key = key_from_ireq(ireq)
-        existing_pin = self.existing_pins.get(key)
+        existing_pin = self._reuse_hashes and self.existing_pins.get(
+            key_from_ireq(ireq)
+        )
         if existing_pin and ireq_satisfied_by_existing_pin(ireq, existing_pin):
             if PIP_VERSION[:2] <= (20, 0):
                 hashes = existing_pin.options.get("hashes", {})
diff --git a/piptools/scripts/compile.py b/piptools/scripts/compile.py
index d96ce9df0..785afb9bb 100755
--- a/piptools/scripts/compile.py
+++ b/piptools/scripts/compile.py
@@ -183,6 +183,15 @@ def has_arg(self, arg_name):
     default=False,
     help="Generate pip 8 style hashes in the resulting requirements file.",
 )
+@click.option(
+    "--reuse-hashes/--no-reuse-hashes",
+    is_flag=True,
+    default=True,
+    help=(
+        "Improve the speed of --generate-hashes by reusing the hashes from an "
+        "existing output file."
+    ),
+)
 @click.option(
     "--max-rounds",
     default=10,
@@ -241,6 +250,7 @@ def cli(
     output_file,
     allow_unsafe,
     generate_hashes,
+    reuse_hashes,
     src_files,
     max_rounds,
     build_isolation,
@@ -360,7 +370,9 @@ def cli(
                 existing_pins_to_upgrade.add(key)
             else:
                 existing_pins[key] = ireq
-        repository = LocalRequirementsRepository(existing_pins, repository)
+        repository = LocalRequirementsRepository(
+            existing_pins, repository, reuse_hashes=reuse_hashes
+        )
 
     ###
     # Parsing/collecting initial requirements
diff --git a/tests/test_repository_local.py b/tests/test_repository_local.py
index c0d4607c5..5b250119e 100644
--- a/tests/test_repository_local.py
+++ b/tests/test_repository_local.py
@@ -1,5 +1,7 @@
 import copy
 
+import pytest
+
 from tests.conftest import FakeRepository
 
 from piptools.repositories.local import LocalRequirementsRepository
@@ -29,6 +31,27 @@ def test_get_hashes_local_repository_cache_hit(from_line, repository):
         assert hashes == EXPECTED
 
 
+NONSENSE = {"sha256:NONSENSE"}
+
+
+@pytest.mark.parametrize(
+    ("reuse_hashes", "expected"), ((True, NONSENSE), (False, EXPECTED))
+)
+def test_toggle_reuse_hashes_local_repository(
+    pip_conf, from_line, pypi_repository, reuse_hashes, expected
+):
+    # Create an install requirement with the hashes included in its options
+    options = {"hashes": {"sha256": [entry.split(":")[1] for entry in NONSENSE]}}
+    req = from_line("small-fake-a==0.1", options=options)
+    existing_pins = {name_from_req(req): req}
+
+    local_repository = LocalRequirementsRepository(
+        existing_pins, pypi_repository, reuse_hashes=reuse_hashes
+    )
+    with local_repository.allow_all_wheels():
+        assert local_repository.get_hashes(from_line("small-fake-a==0.1")) == expected
+
+
 class FakeRepositoryChecksForCopy(FakeRepository):
     def __init__(self):
         super(FakeRepositoryChecksForCopy, self).__init__()