Index: src/wp-signup.php
===================================================================
--- src/wp-signup.php	(revision 33820)
+++ src/wp-signup.php	(working copy)
@@ -28,7 +28,7 @@
 add_action( 'wp_head', 'do_signup_header' );
 
 if ( !is_multisite() ) {
-	wp_redirect( site_url('wp-login.php?action=register') );
+	wp_redirect( wp_registration_url() );
 	die();
 }
 
@@ -669,7 +669,7 @@
 if ( $active_signup == 'none' ) {
 	_e( 'Registration has been disabled.' );
 } elseif ( $active_signup == 'blog' && !is_user_logged_in() ) {
-	$login_url = site_url( 'wp-login.php?redirect_to=' . urlencode( network_site_url( 'wp-signup.php' ) ) );
+	$login_url = wp_login_url( network_site_url( 'wp-signup.php' ) );
 	echo sprintf( __( 'You must first <a href="%s">log in</a>, and then you can create a new site.' ), $login_url );
 } else {
 	$stage = isset( $_POST['stage'] ) ?  $_POST['stage'] : 'default';
Index: src/wp-login.php
===================================================================
--- src/wp-login.php	(revision 33820)
+++ src/wp-login.php	(working copy)
@@ -742,7 +742,7 @@
 	login_header(__('Registration Form'), '<p class="message register">' . __('Register For This Site') . '</p>', $errors);
 ?>
 
-<form name="registerform" id="registerform" action="<?php echo esc_url( site_url('wp-login.php?action=register', 'login_post') ); ?>" method="post" novalidate="novalidate">
+<form name="registerform" id="registerform" action="<?php echo esc_url( wp_registration_url() ); ?>" method="post" novalidate="novalidate">
 	<p>
 		<label for="user_login"><?php _e('Username') ?><br />
 		<input type="text" name="user_login" id="user_login" class="input" value="<?php echo esc_attr(wp_unslash($user_login)); ?>" size="20" /></label>
@@ -908,7 +908,7 @@
 	}
 ?>
 
-<form name="loginform" id="loginform" action="<?php echo esc_url( site_url( 'wp-login.php', 'login_post' ) ); ?>" method="post">
+<form name="loginform" id="loginform" action="<?php echo esc_url( wp_login_url() ); ?>" method="post">
 	<p>
 		<label for="user_login"><?php _e('Username') ?><br />
 		<input type="text" name="log" id="user_login"<?php echo $aria_describedby_error; ?> class="input" value="<?php echo esc_attr( $user_login ); ?>" size="20" /></label>
Index: src/wp-includes/canonical.php
===================================================================
--- src/wp-includes/canonical.php	(revision 33820)
+++ src/wp-includes/canonical.php	(working copy)
@@ -326,7 +326,7 @@
 				/** This filter is documented in wp-login.php */
 				$redirect_url = apply_filters( 'wp_signup_location', network_site_url( 'wp-signup.php' ) );
 			} else {
-				$redirect_url = site_url( 'wp-login.php?action=register' );
+				$redirect_url = wp_registration_url();
 			}
 
 			wp_redirect( $redirect_url, 301 );
@@ -591,7 +591,7 @@
 		site_url( 'login', 'relative' ),
 	);
 	if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $logins ) ) {
-		wp_redirect( site_url( 'wp-login.php', 'login' ) );
+		wp_redirect( wp_login_url() );
 		exit;
 	}
 }
Index: src/wp-admin/network.php
===================================================================
--- src/wp-admin/network.php	(revision 33820)
+++ src/wp-admin/network.php	(working copy)
@@ -556,7 +556,7 @@
 	<?php endif; // end IIS/Apache code branches.
 
 	if ( !is_multisite() ) { ?>
-		<p><?php _e( 'Once you complete these steps, your network is enabled and configured. You will have to log in again.' ); ?> <a href="<?php echo esc_url( site_url( 'wp-login.php' ) ); ?>"><?php _e( 'Log In' ); ?></a></p>
+		<p><?php _e( 'Once you complete these steps, your network is enabled and configured. You will have to log in again.' ); ?> <a href="<?php echo esc_url( wp_login_url() ); ?>"><?php _e( 'Log In' ); ?></a></p>
 <?php
 	}
 }
Index: src/wp-admin/install.php
===================================================================
--- src/wp-admin/install.php	(revision 33820)
+++ src/wp-admin/install.php	(working copy)
@@ -190,7 +190,7 @@
 // Let's check to make sure WP isn't already installed.
 if ( is_blog_installed() ) {
 	display_header();
-	die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p><p class="step"><a href="../wp-login.php" class="button button-large">' . __( 'Log In' ) . '</a></p></body></html>' );
+	die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p><p class="step"><a href="' . esc_url( wp_login_url() ) . '" class="button button-large">' . __( 'Log In' ) . '</a></p></body></html>' );
 }
 
 /**
@@ -341,7 +341,7 @@
 	</tr>
 </table>
 
-<p class="step"><a href="../wp-login.php" class="button button-large"><?php _e( 'Log In' ); ?></a></p>
+<p class="step"><a href="<?php echo esc_url( wp_login_url() ); ?>" class="button button-large"><?php _e( 'Log In' ); ?></a></p>
 
 <?php
 		}
Index: src/wp-activate.php
===================================================================
--- src/wp-activate.php	(revision 33820)
+++ src/wp-activate.php	(working copy)
@@ -14,7 +14,7 @@
 require( dirname( __FILE__ ) . '/wp-blog-header.php' );
 
 if ( !is_multisite() ) {
-	wp_redirect( site_url( '/wp-login.php?action=register' ) );
+	wp_redirect( wp_registration_url() );
 	die();
 }