diff --git a/.tools/cmd/updater/updater.go b/.tools/cmd/updater/updater.go
index a9214a8..4e63f5d 100644
--- a/.tools/cmd/updater/updater.go
+++ b/.tools/cmd/updater/updater.go
@@ -132,8 +132,9 @@ func entrypoint(cmd *cobra.Command, args []string) error {
 		}
 
 		executor := steps.NewExecutor(log, ceSteps, &steps.ExecutorInput{
-			OriginalEbuild: e,
-			LatestVersion:  latestVersion,
+			OriginalEbuild:  e,
+			ExistingEbuilds: ebuilds,
+			LatestVersion:   latestVersion,
 		})
 		res, err := executor.Run(ctx)
 		if err != nil {
diff --git a/.tools/internal/ebuild/ebuild.go b/.tools/internal/ebuild/ebuild.go
index a1e7c93..dd32449 100644
--- a/.tools/internal/ebuild/ebuild.go
+++ b/.tools/internal/ebuild/ebuild.go
@@ -45,6 +45,9 @@ type Ebuild struct {
 	// Raw is the raw ebuild file as it was read from the filesystem.
 	Raw []byte
 
+	// RawName is the raw name of the ebuild as derived from the filename.
+	RawName string
+
 	// EAPI is the EAPI[1] of the ebuild. Only 8 is currently supported.
 	//
 	// [1]: https://wiki.gentoo.org/wiki/EAPI
@@ -181,6 +184,7 @@ func parse(fileName string, b []byte) (*Ebuild, error) {
 	// create the ebuild structure from known variables.
 	ebuild := &Ebuild{
 		Raw:         b,
+		RawName:     filepath.Base(fileName),
 		EAPI:        eapiInt,
 		Name:        name,
 		Category:    filepath.Base(filepath.Dir(filepath.Dir(fileName))),
diff --git a/.tools/internal/steps/ebuild_step.go b/.tools/internal/steps/ebuild_step.go
index b06b3c2..2788bef 100644
--- a/.tools/internal/steps/ebuild_step.go
+++ b/.tools/internal/steps/ebuild_step.go
@@ -57,7 +57,9 @@ func (e EbuildStep) Run(ctx context.Context, env Environment) (*StepOutput, erro
 
 	env.log.Info("generating manifest")
 	if err := stepshelpers.RunCommandInContainer(ctx, env.containerID,
-		"bash", "/generate-manifest.sh", env.in.OriginalEbuild.Category+"/"+env.in.OriginalEbuild.Name, e.path, env.in.LatestVersion,
+		"bash", "/generate-manifest.sh",
+		env.in.OriginalEbuild.Category+"/"+env.in.OriginalEbuild.Name, e.path,
+		WellKnownExistingEbuilds, env.in.LatestVersion,
 	); err != nil {
 		return nil, fmt.Errorf("failed to generate manifest: %w", err)
 	}
diff --git a/.tools/internal/steps/embed/generate-manifest.sh b/.tools/internal/steps/embed/generate-manifest.sh
index e93c356..cef11d3 100644
--- a/.tools/internal/steps/embed/generate-manifest.sh
+++ b/.tools/internal/steps/embed/generate-manifest.sh
@@ -21,17 +21,18 @@ EBUILD_NAME="$1"
 # EBUILD_PATH is the path to the ebuild file that should be used.
 EBUILD_PATH="$2"
 
+EXISTING_EBUILDS_PATH="$3"
+
 # EBUILD_LATEST_VERSION is the latest version of the ebuild.
-EBUILD_LATEST_VERSION="$3"
+EBUILD_LATEST_VERSION="$4"
 
 # MANIFEST_WRITE_PATH is the path to the manifest file that will be
 # written to and read out of by the updater.
 MANIFEST_WRITE_PATH="/.well-known/Manifest"
 
-portdir="/src/fake_portdir/$EBUILD_NAME"
-mkdir -p "$portdir"
+portdir="/src/fake_portdir"
+mkdir -p "$portdir/$EBUILD_NAME" "$portdir/metadata"
 
-mkdir -p "$portdir/metadata"
 # TODO(jaredallard): This should match the repo.
 cat >"$portdir/metadata/layout.conf" <<EOF
 masters = gentoo
@@ -39,11 +40,23 @@ thin-manifests = true
 sign-manifests = false
 EOF
 
-pushd "$portdir" >/dev/null || exit 1
-ebuild_path="$(basename "$EBUILD_NAME")-$EBUILD_LATEST_VERSION.ebuild"
-cp "$EBUILD_PATH" "$ebuild_path"
-chown -R portage:portage .
-ebuild "$ebuild_path" manifest
+pushd "$portdir/$EBUILD_NAME" >/dev/null || exit 1
+
+new_ebuild_path="$(basename "$EBUILD_NAME")-$EBUILD_LATEST_VERSION.ebuild"
+
+# Setup the dir to match what was on the host.
+cp "$EBUILD_PATH" "$new_ebuild_path"
+cp -v "$EXISTING_EBUILDS_PATH"/* .
+chown -R portage:portage "$portdir"
+
+# Generate manifest for each ebuild.
+for ebuild in *.ebuild; do
+  echo " :: Generating manifest for $ebuild"
+  ebuild "$ebuild" manifest
+done
+
+# Write to the manifest file to be read out of later.
 mkdir -p "$(dirname "$MANIFEST_WRITE_PATH")"
 cp Manifest "$MANIFEST_WRITE_PATH"
+
 popd >/dev/null || exit 1
diff --git a/.tools/internal/steps/executor.go b/.tools/internal/steps/executor.go
index 40583dc..920f274 100644
--- a/.tools/internal/steps/executor.go
+++ b/.tools/internal/steps/executor.go
@@ -29,6 +29,13 @@ import (
 	dockerclient "github.com/docker/docker/client"
 )
 
+const (
+	// WellKnownExistingEbuilds is the path in the container where
+	// existing ebuilds are stored for a package. These are older versions
+	// of the current ebuild.
+	WellKnownExistingEbuilds = "/.well-known/existing-ebuilds"
+)
+
 // Executor runs the provided steps inside of a Docker container.
 type Executor struct {
 	log *logger.Logger
@@ -57,6 +64,10 @@ type ExecutorInput struct {
 	// generating a new one.
 	OriginalEbuild *ebuild.Ebuild
 
+	// ExistingEbuilds is a list of existing ebuilds that are already
+	// present that AREN'T the original ebuild.
+	ExistingEbuilds []*ebuild.Ebuild
+
 	// LatestVersion is the latest version of the package.
 	LatestVersion string
 }
diff --git a/.tools/internal/steps/original_ebuild_step.go b/.tools/internal/steps/original_ebuild_step.go
index 1742491..2ea9dec 100644
--- a/.tools/internal/steps/original_ebuild_step.go
+++ b/.tools/internal/steps/original_ebuild_step.go
@@ -25,6 +25,8 @@ import (
 
 // OriginalEbuildStep is a step that writes the source ebuild into the
 // filesystem of the container at the provided path.
+//
+// Also populates the existing ebuilds directory for usage later.
 type OriginalEbuildStep struct {
 	// path is the path to write the ebuild to in the container.
 	path string
@@ -47,5 +49,19 @@ func (e OriginalEbuildStep) Run(ctx context.Context, env Environment) (*StepOutp
 		outputPath = filepath.Join(env.workDir, e.path)
 	}
 
-	return nil, stepshelpers.CopyFileBytesToContainer(ctx, env.containerID, env.in.OriginalEbuild.Raw, outputPath)
+	if err := stepshelpers.CopyFileBytesToContainer(ctx, env.containerID, env.in.OriginalEbuild.Raw, outputPath); err != nil {
+		return nil, fmt.Errorf("failed to copy ebuild to container: %w", err)
+	}
+
+	// Best effort create the existing ebuilds directory.
+	stepshelpers.RunCommandInContainer(ctx, env.containerID, "mkdir", "-p", WellKnownExistingEbuilds)
+
+	for _, e := range env.in.ExistingEbuilds {
+		env.log.With("ebuild", e.RawName).Debug("copying existing ebuild to container")
+		if err := stepshelpers.CopyFileBytesToContainer(ctx, env.containerID, e.Raw, filepath.Join(WellKnownExistingEbuilds, e.RawName)); err != nil {
+			return nil, fmt.Errorf("failed to copy existing ebuild to container: %w", err)
+		}
+	}
+
+	return &StepOutput{}, nil
 }
diff --git a/Dockerfile b/Dockerfile
index 6b4aa91..4ab6f3a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,9 @@
 # Used as the base image for elint and updater.
 FROM gentoo/stage3
 WORKDIR "/src/updater"
-ENTRYPOINT [ "/usr/local/bin/updater" ]
 
-RUN emerge-webrsync
-RUN emerge -v dev-vcs/git && ACCEPT_KEYWORDS="~amd64 ~arm64" emerge -v app-portage/pycargoebuild
\ No newline at end of file
+RUN emerge-webrsync && \
+  emerge -v dev-vcs/git && \
+  ACCEPT_KEYWORDS="~amd64 ~arm64" emerge -v app-portage/pycargoebuild && \
+  emerge -v app-portage/gentoolkit && \
+  eclean --deep packages && eclean --deep distfiles