diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index c898cbf18a..c60f1df7ba 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -3386,12 +3386,6 @@ function wp_update_term( $term_id, $taxonomy, $args = array() ) {
 
 	$tt_id = $wpdb->get_var( $wpdb->prepare( "SELECT tt.term_taxonomy_id FROM $wpdb->term_taxonomy AS tt INNER JOIN $wpdb->terms AS t ON tt.term_id = t.term_id WHERE tt.taxonomy = %s AND t.term_id = %d", $taxonomy, $term_id) );
 
-	// Check whether this is a shared term that needs splitting.
-	$_term_id = _split_shared_term( $term_id, $tt_id );
-	if ( ! is_wp_error( $_term_id ) ) {
-		$term_id = $_term_id;
-	}
-
 	/**
 	 * Fires immediately before the given terms are edited.
 	 *
@@ -4045,62 +4039,6 @@ function _update_generic_term_count( $terms, $taxonomy ) {
 	}
 }
 
-/**
- * Create a new term for a term_taxonomy item that currently shares its term.
- *
- * @since 4.1.0
- * @access private
- *
- * @param int   $term_id          ID of the shared term.
- * @param int   $term_taxonomy_id ID of the term taxonomy item to receive a new term.
- * @param array $shared_tts       Sibling term taxonomies, used for busting caches.
- * @return int  Term ID.
- */
-function _split_shared_term( $term_id, $term_taxonomy_id ) {
-	global $wpdb;
-
-	// Don't try to split terms if database schema does not support shared slugs.
-	$current_db_version = get_option( 'db_version' );
-	if ( $current_db_version < 30133 ) {
-		return $term_id;
-	}
-
-	// If there are no shared term_taxonomy rows, there's nothing to do here.
-	$shared_tt_count = $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->term_taxonomy tt WHERE tt.term_id = %d AND tt.term_taxonomy_id != %d", $term_id, $term_taxonomy_id ) );
-	if ( ! $shared_tt_count ) {
-		return $term_id;
-	}
-
-	// Pull up data about the currently shared slug, which we'll use to populate the new one.
-	$shared_term = $wpdb->get_row( $wpdb->prepare( "SELECT t.* FROM $wpdb->terms t WHERE t.term_id = %d", $term_id ) );
-
-	$new_term_data = array(
-		'name' => $shared_term->name,
-		'slug' => $shared_term->slug,
-		'term_group' => $shared_term->term_group,
-	);
-
-	if ( false === $wpdb->insert( $wpdb->terms, $new_term_data ) ) {
-		return new WP_Error( 'db_insert_error', __( 'Could not split shared term.' ), $wpdb->last_error );
-	}
-
-	$new_term_id = (int) $wpdb->insert_id;
-
-	// Update the existing term_taxonomy to point to the newly created term.
-	$wpdb->update( $wpdb->term_taxonomy,
-		array( 'term_id' => $new_term_id ),
-		array( 'term_taxonomy_id' => $term_taxonomy_id )
-	);
-
-	// Clean the cache for term taxonomies formerly shared with the current term.
-	$shared_term_taxonomies = $wpdb->get_row( $wpdb->prepare( "SELECT taxonomy FROM $wpdb->term_taxonomy WHERE term_id = %d", $term_id ) );
-	foreach ( (array) $shared_term_taxonomies as $shared_term_taxonomy ) {
-		clean_term_cache( $term_id, $shared_term_taxonomy );
-	}
-
-	return $new_term_id;
-}
-
 /**
  * Generate a permalink for a taxonomy term archive.
  *
diff --git a/tests/phpunit/tests/term.php b/tests/phpunit/tests/term.php
index 1258c4b120..2cf5fb278c 100644
--- a/tests/phpunit/tests/term.php
+++ b/tests/phpunit/tests/term.php
@@ -690,88 +690,6 @@ class Tests_Term extends WP_UnitTestCase {
 		$this->assertSame( 'duplicate_term_slug', $updated->get_error_code() );
 	}
 
-	/**
-	 * @ticket 5809
-	 */
-	public function test_wp_update_term_should_split_shared_term() {
-		global $wpdb;
-
-		register_taxonomy( 'wptests_tax', 'post' );
-		register_taxonomy( 'wptests_tax_2', 'post' );
-
-		$t1 = wp_insert_term( 'Foo', 'wptests_tax' );
-		$t2 = wp_insert_term( 'Foo', 'wptests_tax_2' );
-
-		// Manually modify because split terms shouldn't naturally occur.
-		$wpdb->update( $wpdb->term_taxonomy,
-			array( 'term_id' => $t1['term_id'] ),
-			array( 'term_taxonomy_id' => $t2['term_taxonomy_id'] ),
-			array( '%d' ),
-			array( '%d' )
-		);
-
-		$posts = $this->factory->post->create_many( 2 );
-		wp_set_object_terms( $posts[0], array( 'Foo' ), 'wptests_tax' );
-		wp_set_object_terms( $posts[1], array( 'Foo' ), 'wptests_tax_2' );
-
-		// Verify that the terms are shared.
-		$t1_terms = wp_get_object_terms( $posts[0], 'wptests_tax' );
-		$t2_terms = wp_get_object_terms( $posts[1], 'wptests_tax_2' );
-		$this->assertSame( $t1_terms[0]->term_id, $t2_terms[0]->term_id );
-
-		wp_update_term( $t2_terms[0]->term_id, 'wptests_tax_2', array(
-			'name' => 'New Foo',
-		) );
-
-		$t1_terms = wp_get_object_terms( $posts[0], 'wptests_tax' );
-		$t2_terms = wp_get_object_terms( $posts[1], 'wptests_tax_2' );
-		$this->assertNotEquals( $t1_terms[0]->term_id, $t2_terms[0]->term_id );
-	}
-
-	/**
-	 * @ticket 5809
-	 */
-	public function test_wp_update_term_should_not_split_shared_term_before_410_schema_change() {
-		global $wpdb;
-
-		$db_version = get_option( 'db_version' );
-		update_option( 'db_version', 30055 );
-
-		register_taxonomy( 'wptests_tax', 'post' );
-		register_taxonomy( 'wptests_tax_2', 'post' );
-
-		$t1 = wp_insert_term( 'Foo', 'wptests_tax' );
-		$t2 = wp_insert_term( 'Foo', 'wptests_tax_2' );
-
-		// Manually modify because split terms shouldn't naturally occur.
-		$wpdb->update( $wpdb->term_taxonomy,
-			array( 'term_id' => $t1['term_id'] ),
-			array( 'term_taxonomy_id' => $t2['term_taxonomy_id'] ),
-			array( '%d' ),
-			array( '%d' )
-		);
-
-		$posts = $this->factory->post->create_many( 2 );
-		wp_set_object_terms( $posts[0], array( 'Foo' ), 'wptests_tax' );
-		wp_set_object_terms( $posts[1], array( 'Foo' ), 'wptests_tax_2' );
-
-		// Verify that the term is shared.
-		$t1_terms = wp_get_object_terms( $posts[0], 'wptests_tax' );
-		$t2_terms = wp_get_object_terms( $posts[1], 'wptests_tax_2' );
-		$this->assertSame( $t1_terms[0]->term_id, $t2_terms[0]->term_id );
-
-		wp_update_term( $t2_terms[0]->term_id, 'wptests_tax_2', array(
-			'name' => 'New Foo',
-		) );
-
-		// Term should still be shared.
-		$t1_terms = wp_get_object_terms( $posts[0], 'wptests_tax' );
-		$t2_terms = wp_get_object_terms( $posts[1], 'wptests_tax_2' );
-		$this->assertSame( $t1_terms[0]->term_id, $t2_terms[0]->term_id );
-
-		update_option( 'db_version', $db_version );
-	}
-
 	public function test_wp_update_term_alias_of_no_term_group() {
 		register_taxonomy( 'wptests_tax', 'post' );
 		$t1 = $this->factory->term->create( array(