diff --git a/README.md b/README.md
index e7cdb56d..6bee71c8 100644
--- a/README.md
+++ b/README.md
@@ -23,8 +23,7 @@ available attached to tagged [releases].
 #### `prepare [APPLICATION] --build-dir [BUILD-DIR] --source-dir [SOURCE-DIR]`
 
 In the prepare step, `slugcmplr` will fetch the metadata required to compile
-your application. It will copy your project `SOURCE-DIR` into `BUILD-DIR/app`
-(it currently do not respect your `.slugcleanup` file, this is TODO).
+your application. It will copy your project `SOURCE-DIR` into `BUILD-DIR/app`.
 
 It will fetch the buildpacks as defined by your Heroku application download and
 decompress them into `BUILD-DIR/buildpacks`. If using official buildpacks (e.g.
diff --git a/go.mod b/go.mod
index ac960e22..d21f44df 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.16
 
 require (
 	github.com/bgentry/go-netrc v0.0.0-20140422174119-9fd32a8b3d3d
+	github.com/bmatcuk/doublestar/v4 v4.0.2
 	github.com/go-git/go-git/v5 v5.4.2
 	github.com/heroku/heroku-go/v5 v5.3.0
 	github.com/otiai10/copy v1.6.0
diff --git a/go.sum b/go.sum
index ae4a7550..c15d6f86 100644
--- a/go.sum
+++ b/go.sum
@@ -58,6 +58,8 @@ github.com/bgentry/go-netrc v0.0.0-20140422174119-9fd32a8b3d3d h1:xDfNPAt8lFiC1U
 github.com/bgentry/go-netrc v0.0.0-20140422174119-9fd32a8b3d3d/go.mod h1:6QX/PXZ00z/TKoufEY6K/a0k6AhaJrQKdFe6OfVXsa4=
 github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
 github.com/bketelsen/crypt v0.0.4/go.mod h1:aI6NrJ0pMGgvZKL1iVgXLnfIFJtfV+bKCoqOes/6LfM=
+github.com/bmatcuk/doublestar/v4 v4.0.2 h1:X0krlUVAVmtr2cRoTqR8aDMrDqnB36ht8wpWTiQ3jsA=
+github.com/bmatcuk/doublestar/v4 v4.0.2/go.mod h1:xBQ8jztBU6kakFMg+8WGxn0c6z1fTSPVIjEY1Wr7jzc=
 github.com/cenkalti/backoff v2.1.1+incompatible h1:tKJnvO2kl0zmb/jA5UKAt4VoEVw1qxKWjE/Bpp46npY=
 github.com/cenkalti/backoff v2.1.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
diff --git a/main_test.go b/main_test.go
index 8b247da4..928257a9 100644
--- a/main_test.go
+++ b/main_test.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 	"testing"
 
@@ -22,6 +23,7 @@ func Test_Suite(t *testing.T) {
 	// nolint: paralleltest
 	t.Run("End to end tests", func(t *testing.T) {
 		t.Run("TestDetectFail", testDetectFail)
+		t.Run("TestSlugIgnore", testSlugIgnore)
 		t.Run("TestPrepare", testPrepare)
 		t.Run("TestGo", testGo)
 		t.Run("TestRails", testRails)
@@ -163,6 +165,55 @@ func testDetectFail(t *testing.T) {
 	})
 }
 
+func testSlugIgnore(t *testing.T) {
+	t.Parallel()
+
+	buildpacks := []*BuildpackDescription{
+		{URL: "https://github.com/CGA1123/heroku-buildpack-bar", Name: "CGA1123/heroku-buildpack-bar"},
+		{URL: "https://github.com/CGA1123/heroku-buildpack-foo", Name: "CGA1123/heroku-buildpack-foo"},
+	}
+
+	configVars := map[string]string{"FOO": "BAR", "BAR": "FOO"}
+
+	withStubPrepare(t, "CGA1123/slugcmplr-fixture-slugignore", buildpacks, configVars, func(t *testing.T, app, buildDir string) {
+		foundPaths := []string{}
+		expectedPaths := []string{
+			"/README.md",
+			"/.slugignore",
+			"/keep-me/hello.txt",
+			"/vendor/keep-this-dir/file-1.txt",
+			"/vendor/keep-this-dir/file-2.txt",
+		}
+
+		err := filepath.Walk(filepath.Join(buildDir, buildpack.AppDir), func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				t.Fatalf("error while walking directory: %v", err)
+			}
+
+			if info.Mode().IsRegular() {
+				foundPaths = append(foundPaths, strings.TrimPrefix(path, filepath.Join(buildDir, buildpack.AppDir)))
+			}
+
+			return nil
+		})
+		if err != nil {
+			t.Fatalf("filepath.Walk error: %v", err)
+		}
+
+		sort.Strings(foundPaths)
+		sort.Strings(expectedPaths)
+
+		if !SliceEqual(foundPaths, expectedPaths, func(i int) bool {
+			return foundPaths[i] == expectedPaths[i]
+		}) {
+			expected := strings.Join(expectedPaths, "\n")
+			actual := strings.Join(foundPaths, "\n")
+
+			t.Fatalf("\nexpected:\n%v\n---\nactual:\n%v\n", expected, actual)
+		}
+	})
+}
+
 func testBinary(t *testing.T) {
 	t.Parallel()
 
diff --git a/prepare.go b/prepare.go
index 667d8dbd..57fba7a7 100644
--- a/prepare.go
+++ b/prepare.go
@@ -7,8 +7,10 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
 
 	"github.com/cga1123/slugcmplr/buildpack"
+	"github.com/cga1123/slugcmplr/slugignore"
 	"github.com/otiai10/copy"
 	"github.com/spf13/cobra"
 )
@@ -100,8 +102,19 @@ func prepare(ctx context.Context, cmd Outputter, p *Prepare) error {
 	log(cmd, "From: %v", p.SourceDir)
 	log(cmd, "To: %v", appDir)
 
+	ignore, err := slugignore.ForDirectory(p.SourceDir)
+	if err != nil {
+		return fmt.Errorf("failed to read .slugignore: %v", err)
+	}
+
 	// copy source
-	if err := copy.Copy(p.SourceDir, appDir); err != nil {
+	if err := copy.Copy(p.SourceDir, appDir, copy.Options{
+		Skip: func(path string) (bool, error) {
+			return ignore.IsIgnored(
+				strings.TrimPrefix(path, p.SourceDir),
+			), nil
+		},
+	}); err != nil {
 		return fmt.Errorf("failed to copy source: %w", err)
 	}
 
diff --git a/slugignore/slugignore.go b/slugignore/slugignore.go
new file mode 100644
index 00000000..f175d632
--- /dev/null
+++ b/slugignore/slugignore.go
@@ -0,0 +1,113 @@
+// package slugignore implements Heroku-like .slugignore functionality for a
+// given directory.
+//
+// Heroku's .slugignore format treats all non-empty and non comment lines
+// (comment lines are those beginning with a # characted) as Ruby Dir globs,
+package slugignore
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/bmatcuk/doublestar/v4"
+)
+
+// SlugIgnore is the interface for a parsed .slugignore file
+//
+// A given SlugIgnore is only applicable to the directory which contains the
+// .slugignore file, at the time at which it was parsed.
+type SlugIgnore interface {
+	IsIgnored(path string) bool
+}
+
+// ForDirectory parses the .slugignore for a given directory.
+//
+// If there is no .slugignore file found, it returns a SlugIgnore which always
+// returns false when IsIgnored is called.
+func ForDirectory(dir string) (SlugIgnore, error) {
+	f, err := os.Open(filepath.Join(dir, ".slugignore"))
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return &nullSlugIgnore{}, nil
+		}
+
+		return nil, err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(bufio.NewReader(f))
+	globs := []string{}
+
+	for s.Scan() {
+		line := s.Text()
+		if strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+
+		trimmed := strings.TrimPrefix(line, "/")
+		if strings.HasPrefix(line, "/") {
+			globs = append(globs, trimmed)
+		} else {
+			globs = append(
+				globs,
+				trimmed,
+				filepath.Join("**", trimmed),
+			)
+		}
+	}
+	if err := s.Err(); err != nil {
+		return nil, fmt.Errorf("error parsing .slugignore: %w", err)
+	}
+
+	ignored := map[string]struct{}{}
+	for _, glob := range globs {
+		if !doublestar.ValidatePattern(glob) {
+			return nil, fmt.Errorf("slugignore pattern is malformed: %v", glob)
+		}
+
+		matches, err := doublestar.Glob(os.DirFS(dir), glob)
+		if err != nil {
+			return nil, fmt.Errorf("error expanding glob %v: %w", glob, err)
+		}
+
+		for _, match := range matches {
+			ignored[match] = struct{}{}
+		}
+	}
+
+	return cache(ignored), nil
+}
+
+type nullSlugIgnore struct{}
+
+func (*nullSlugIgnore) IsIgnored(path string) bool {
+	return false
+}
+
+type cache map[string]struct{}
+
+func (c cache) IsIgnored(path string) bool {
+	path = strings.TrimPrefix(path, "/")
+
+	for {
+		if _, ok := c[path]; ok {
+			return true
+		}
+
+		path = filepath.Join(path, "..")
+
+		if path == "." {
+			break
+		}
+	}
+
+	return false
+}