diff --git a/cli/command/image/build.go b/cli/command/image/build.go
index 1da0b31c55..dce178a71b 100644
--- a/cli/command/image/build.go
+++ b/cli/command/image/build.go
@@ -8,7 +8,6 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
-	"path/filepath"
 	"regexp"
 	"runtime"
 	"time"
@@ -20,10 +19,8 @@ import (
 	"github.com/docker/docker/api"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/container"
-	"github.com/docker/docker/builder/dockerignore"
 	"github.com/docker/docker/opts"
 	"github.com/docker/docker/pkg/archive"
-	"github.com/docker/docker/pkg/fileutils"
 	"github.com/docker/docker/pkg/jsonmessage"
 	"github.com/docker/docker/pkg/progress"
 	"github.com/docker/docker/pkg/streamformatter"
@@ -208,22 +205,13 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {
 	}
 
 	if buildCtx == nil {
-		f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
-		if err != nil && !os.IsNotExist(err) {
+		excludes, err := build.ReadDockerignore(contextDir)
+		if err != nil {
 			return err
 		}
-		defer f.Close()
-
-		var excludes []string
-		if err == nil {
-			excludes, err = dockerignore.ReadAll(f)
-			if err != nil {
-				return err
-			}
-		}
 
 		if err := build.ValidateContextDirectory(contextDir, excludes); err != nil {
-			return errors.Errorf("Error checking context: '%s'.", err)
+			return errors.Errorf("error checking context: '%s'.", err)
 		}
 
 		// And canonicalize dockerfile name to a platform-independent one
@@ -232,20 +220,7 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {
 			return errors.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)
 		}
 
-		// If .dockerignore mentions .dockerignore or the Dockerfile then make
-		// sure we send both files over to the daemon because Dockerfile is,
-		// obviously, needed no matter what, and .dockerignore is needed to know
-		// if either one needs to be removed. The daemon will remove them
-		// if necessary, after it parses the Dockerfile. Ignore errors here, as
-		// they will have been caught by validateContextDirectory above.
-		// Excludes are used instead of includes to maintain the order of files
-		// in the archive.
-		if keep, _ := fileutils.Matches(".dockerignore", excludes); keep {
-			excludes = append(excludes, "!.dockerignore")
-		}
-		if keep, _ := fileutils.Matches(relDockerfile, excludes); keep && !options.dockerfileFromStdin() {
-			excludes = append(excludes, "!"+relDockerfile)
-		}
+		excludes = build.TrimBuildFilesFromExcludes(excludes, relDockerfile, options.dockerfileFromStdin())
 
 		compression := archive.Uncompressed
 		if options.compress {
diff --git a/cli/command/image/build/context.go b/cli/command/image/build/context.go
index af1892b96c..83a90c9f15 100644
--- a/cli/command/image/build/context.go
+++ b/cli/command/image/build/context.go
@@ -143,7 +143,7 @@ func GetContextFromGitURL(gitURL, dockerfileName string) (string, string, error)
 		return "", "", errors.Wrapf(err, "unable to 'git clone' to temporary context directory")
 	}
 
-	absContextDir, err = resolveAndValidateContextPath(absContextDir)
+	absContextDir, err = ResolveAndValidateContextPath(absContextDir)
 	if err != nil {
 		return "", "", err
 	}
@@ -173,7 +173,7 @@ func GetContextFromURL(out io.Writer, remoteURL, dockerfileName string) (io.Read
 // the relative path of the dockerfile in that context directory, and a non-nil
 // error on success.
 func GetContextFromLocalDir(localDir, dockerfileName string) (string, string, error) {
-	localDir, err := resolveAndValidateContextPath(localDir)
+	localDir, err := ResolveAndValidateContextPath(localDir)
 	if err != nil {
 		return "", "", err
 	}
@@ -191,9 +191,9 @@ func GetContextFromLocalDir(localDir, dockerfileName string) (string, string, er
 	return localDir, relDockerfile, err
 }
 
-// resolveAndValidateContextPath uses the given context directory for a `docker build`
+// ResolveAndValidateContextPath uses the given context directory for a `docker build`
 // and returns the absolute path to the context directory.
-func resolveAndValidateContextPath(givenContextDir string) (string, error) {
+func ResolveAndValidateContextPath(givenContextDir string) (string, error) {
 	absContextDir, err := filepath.Abs(givenContextDir)
 	if err != nil {
 		return "", errors.Errorf("unable to get absolute context directory of given context directory %q: %v", givenContextDir, err)
diff --git a/cli/command/image/build/dockerignore.go b/cli/command/image/build/dockerignore.go
new file mode 100644
index 0000000000..497c3f24f3
--- /dev/null
+++ b/cli/command/image/build/dockerignore.go
@@ -0,0 +1,39 @@
+package build
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/docker/docker/builder/dockerignore"
+	"github.com/docker/docker/pkg/fileutils"
+)
+
+// ReadDockerignore reads the .dockerignore file in the context directory and
+// returns the list of paths to exclude
+func ReadDockerignore(contextDir string) ([]string, error) {
+	var excludes []string
+
+	f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
+	switch {
+	case os.IsNotExist(err):
+		return excludes, nil
+	case err != nil:
+		return nil, err
+	}
+	defer f.Close()
+
+	return dockerignore.ReadAll(f)
+}
+
+// TrimBuildFilesFromExcludes removes the named Dockerfile and .dockerignore from
+// the list of excluded files. The daemon will remove them from the final context
+// but they must be in available in the context when passed to the API.
+func TrimBuildFilesFromExcludes(excludes []string, dockerfile string, dockerfileFromStdin bool) []string {
+	if keep, _ := fileutils.Matches(".dockerignore", excludes); keep {
+		excludes = append(excludes, "!.dockerignore")
+	}
+	if keep, _ := fileutils.Matches(dockerfile, excludes); keep && !dockerfileFromStdin {
+		excludes = append(excludes, "!"+dockerfile)
+	}
+	return excludes
+}