diff --git a/builder/dispatchers.go b/builder/dispatchers.go
index 82bb6ce5fd..0c2a580872 100644
--- a/builder/dispatchers.go
+++ b/builder/dispatchers.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/docker/docker/nat"
@@ -129,7 +130,7 @@ func onbuild(b *Builder, args []string, attributes map[string]bool, original str
 		return fmt.Errorf("%s isn't allowed as an ONBUILD trigger", triggerInstruction)
 	}
 
-	original = strings.TrimSpace(strings.TrimLeft(original, "ONBUILD"))
+	original = regexp.MustCompile(`(?i)^\s*ONBUILD\s*`).ReplaceAllString(original, "")
 
 	b.Config.OnBuild = append(b.Config.OnBuild, original)
 	return b.commit("", b.Config.Cmd, fmt.Sprintf("ONBUILD %s", original))
diff --git a/integration-cli/docker_cli_build_test.go b/integration-cli/docker_cli_build_test.go
index 12b8e00b6f..c909b14f0d 100644
--- a/integration-cli/docker_cli_build_test.go
+++ b/integration-cli/docker_cli_build_test.go
@@ -15,6 +15,41 @@ import (
 	"github.com/docker/docker/pkg/archive"
 )
 
+func TestBuildOnBuildLowercase(t *testing.T) {
+	name := "testbuildonbuildlowercase"
+	name2 := "testbuildonbuildlowercase2"
+
+	defer deleteImages(name, name2)
+
+	_, err := buildImage(name,
+		`
+  FROM busybox
+  onbuild run echo quux
+  `, true)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, out, err := buildImageWithOut(name2, fmt.Sprintf(`
+  FROM %s
+  `, name), true)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !strings.Contains(out, "quux") {
+		t.Fatalf("Did not receive the expected echo text, got %s", out)
+	}
+
+	if strings.Contains(out, "ONBUILD ONBUILD") {
+		t.Fatalf("Got an ONBUILD ONBUILD error with no error: got %s", out)
+	}
+
+	logDone("build - handle case-insensitive onbuild statement")
+}
+
 func TestBuildEnvEscapes(t *testing.T) {
 	name := "testbuildenvescapes"
 	defer deleteAllContainers()