apply plugin: 'com.android.application'

android {
    ...

    defaultConfig {
        ...
        systemProp.http.proxyHost=proxy.company.com
        systemProp.http.proxyPort=443
        systemProp.http.proxyUser=userid
        systemProp.http.proxyPassword=password
        systemProp.http.auth.ntlm.domain=domain
    }
    ...
}

# Project-wide Gradle settings.
...

systemProp.http.proxyHost=proxy.company.com
systemProp.http.proxyPort=443
systemProp.http.proxyUser=username
systemProp.http.proxyPassword=password
systemProp.http.auth.ntlm.domain=domain

systemProp.https.proxyHost=proxy.company.com
systemProp.https.proxyPort=443
systemProp.https.proxyUser=username
systemProp.https.proxyPassword=password
systemProp.https.auth.ntlm.domain=domain

...