diff --git a/src/wp-admin/includes/post.php b/src/wp-admin/includes/post.php
index bd13630062..13d9d44bd8 100644
--- a/src/wp-admin/includes/post.php
+++ b/src/wp-admin/includes/post.php
@@ -314,6 +314,47 @@ function edit_post( $post_data = null ) {
 		$post_data = apply_filters( 'attachment_fields_to_save', $post_data, $attachment_data );
 	}
 
+	// Convert taxonomy input to term IDs, to avoid ambiguity.
+	if ( isset( $post_data['tax_input'] ) ) {
+		foreach ( (array) $post_data['tax_input'] as $taxonomy => $terms ) {
+			// Hierarchical taxonomy data is already sent as term IDs, so no conversion is necessary.
+			if ( is_taxonomy_hierarchical( $taxonomy ) ) {
+				continue;
+			}
+
+			/*
+			 * Assume that a 'tax_input' string is a comma-separated list of term names.
+			 * Some languages may use a character other than a comma as a delimiter, so we standardize on
+			 * commas before parsing the list.
+			 */
+			if ( ! is_array( $terms ) ) {
+				$comma = _x( ',', 'tag delimiter' );
+				if ( ',' !== $comma ) {
+					$terms = str_replace( $comma, ',', $terms );
+				}
+				$terms = explode( ',', trim( $terms, " \n\t\r\0\x0B," ) );
+			}
+
+			$clean_terms = array();
+			foreach ( $terms as $term ) {
+				$_term = get_terms( $taxonomy, array(
+					'name' => $term,
+					'fields' => 'ids',
+					'hide_empty' => false,
+				) );
+
+				if ( ! empty( $_term ) ) {
+					$clean_terms[] = intval( $_term[0] );
+				} else {
+					// No existing term was found, so pass the string. A new term will be created.
+					$clean_terms[] = $term;
+				}
+			}
+
+			$post_data['tax_input'][ $taxonomy ] = $clean_terms;
+		}
+	}
+
 	add_meta( $post_ID );
 
 	update_post_meta( $post_ID, '_edit_last', get_current_user_id() );
diff --git a/tests/phpunit/tests/admin/includesPost.php b/tests/phpunit/tests/admin/includesPost.php
index 4ba3de71df..647ff61ecd 100644
--- a/tests/phpunit/tests/admin/includesPost.php
+++ b/tests/phpunit/tests/admin/includesPost.php
@@ -136,6 +136,45 @@ class Tests_Admin_includesPost extends WP_UnitTestCase {
 		$this->assertEquals( 'draft', get_post( $post->ID )->post_status );
 	}
 
+	/**
+	 * @ticket 30615
+	 */
+	public function test_edit_post_should_parse_tax_input_by_name_rather_than_slug_for_nonhierarchical_taxonomies() {
+		$u = $this->factory->user->create( array( 'role' => 'editor' ) );
+		wp_set_current_user( $u );
+
+		register_taxonomy( 'wptests_tax', array( 'post' ) );
+		$t1 = $this->factory->term->create( array(
+			'taxonomy' => 'wptests_tax',
+			'name' => 'foo',
+			'slug' => 'bar',
+		) );
+		$t2 = $this->factory->term->create( array(
+			'taxonomy' => 'wptests_tax',
+			'name' => 'bar',
+			'slug' => 'foo',
+		) );
+
+		$p = $this->factory->post->create();
+
+		$post_data = array(
+			'post_ID' => $p,
+			'tax_input' => array(
+				'wptests_tax' => 'foo,baz',
+			),
+		);
+
+		edit_post( $post_data );
+
+		$found = wp_get_post_terms( $p, 'wptests_tax' );
+
+		// Should contain the term with the name 'foo', not the slug.
+		$this->assertContains( $t1, wp_list_pluck( $found, 'term_id' ) );
+
+		// The 'baz' tag should have been created.
+		$this->assertContains( 'baz', wp_list_pluck( $found, 'name' ) );
+	}
+
 	/**
 	 * @ticket 27792
 	 */