btn_borderless.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_pressed="true"
        android:drawable="@drawable/button_default_pressed"/>
    <item
        android:drawable="@drawable/btn_borderless_normal"/>
</selector>

btn_default_normal.xml

<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:insetLeft="@dimen/button_inset_horizontal_material"
    android:insetTop="@dimen/button_inset_vertical_material"
    android:insetRight="@dimen/button_inset_horizontal_material"
    android:insetBottom="@dimen/button_inset_vertical_material">
    <shape android:shape="rectangle">
        <corners android:radius="@dimen/control_corner_material" />
        <solid android:color="@color/buttonNormal" />
        <padding android:left="@dimen/button_padding_horizontal_material"
            android:top="@dimen/button_padding_vertical_material"
            android:right="@dimen/button_padding_horizontal_material"
            android:bottom="@dimen/button_padding_vertical_material" />
    </shape>
</inset>

button_default_pressed.xml

<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:insetLeft="@dimen/button_inset_horizontal_material"
    android:insetTop="@dimen/button_inset_vertical_material"
    android:insetRight="@dimen/button_inset_horizontal_material"
    android:insetBottom="@dimen/button_inset_vertical_material">
    <shape android:shape="rectangle">
        <corners android:radius="@dimen/control_corner_material" />
        <solid android:color="@color/buttonPressed" />
        <padding android:left="@dimen/button_padding_horizontal_material"
            android:top="@dimen/button_padding_vertical_material"
            android:right="@dimen/button_padding_horizontal_material"
            android:bottom="@dimen/button_padding_vertical_material" />
    </shape>
</inset>

styles(v21).xml

<style name="AppTheme.Widget.BorderlessButton" parent="android:Widget.Material.Button.Borderless" />

styles.xml

<style name="AppTheme.Widget.BorderlessButton">
        <item name="android:background">@drawable/btn_borderless</item>
        <item name="android:textAllCaps">true</item>
        <item name="android:textColor">@color/button_label</item>
</style>