@@ -6,7 +6,7 @@ import "fmt"

 // a command not supported on the platform.

 func platformSupports(command string) error {

 	switch command {

-	case "user", "stopsignal", "arg":

+	case "user", "stopsignal":

 		return fmt.Errorf("The daemon on this platform does not support the command '%s'", command)

 	}

 	return nil

@@ -7,6 +7,7 @@ import (

 	"os"

 	"path/filepath"

+	"github.com/docker/docker/utils"

 	"github.com/docker/docker/volume"

 	containertypes "github.com/docker/engine-api/types/container"

 )

@@ -30,8 +31,10 @@ type ExitStatus struct {

 // CreateDaemonEnvironment creates a new environment variable slice for this container.

 func (container *Container) CreateDaemonEnvironment(linkedEnv []string) []string {

-	// On Windows, nothing to link. Just return the container environment.

-	return container.Config.Env

+	// because the env on the container can override certain default values

+	// we need to replace the 'env' keys where they match and append anything

+	// else.

+	return utils.ReplaceOrAppendEnvValues(linkedEnv, container.Config.Env)

 }

 // UnmountIpcMounts unmount Ipc related mounts.

@@ -6171,17 +6171,24 @@ func (s *DockerSuite) TestBuildStopSignal(c *check.C) {

 }

 func (s *DockerSuite) TestBuildBuildTimeArg(c *check.C) {

-	testRequires(c, DaemonIsLinux) // Windows does not support ARG

 	imgName := "bldargtest"

 	envKey := "foo"

 	envVal := "bar"

-	args := []string{

-		"--build-arg", fmt.Sprintf("%s=%s", envKey, envVal),

+	args := []string{"--build-arg", fmt.Sprintf("%s=%s", envKey, envVal)}

+	var dockerfile string

+	if daemonPlatform == "windows" {

+		// Bugs in Windows busybox port - use the default base image and native cmd stuff

+		dockerfile = fmt.Sprintf(`FROM `+minimalBaseImage()+`

+			ARG %s

+			RUN echo %%%s%%

+			CMD setlocal enableextensions && if defined %s (echo %%%s%%)`, envKey, envKey, envKey, envKey)

+	} else {

+		dockerfile = fmt.Sprintf(`FROM busybox

+			ARG %s

+			RUN echo $%s

+			CMD echo $%s`, envKey, envKey, envKey)

+

 	}

-	dockerfile := fmt.Sprintf(`FROM busybox

-		ARG %s

-		RUN echo $%s

-		CMD echo $%s`, envKey, envKey, envKey)

 	if _, out, err := buildImageWithOut(imgName, dockerfile, true, args...); err != nil || !strings.Contains(out, envVal) {

 		if err != nil {

@@ -6191,7 +6198,9 @@ func (s *DockerSuite) TestBuildBuildTimeArg(c *check.C) {

 	}

 	containerName := "bldargCont"

-	if out, _ := dockerCmd(c, "run", "--name", containerName, imgName); out != "\n" {

+	out, _ := dockerCmd(c, "run", "--name", containerName, imgName)

+	out = strings.Trim(out, " \r\n'")

+	if out != "" {

 		c.Fatalf("run produced invalid output: %q, expected empty string", out)

 	}

 }