diff --git a/src/applications/project/controller/PhabricatorProjectBoardImportController.php b/src/applications/project/controller/PhabricatorProjectBoardImportController.php
index 67bddaaa52..89a01e8db1 100644
--- a/src/applications/project/controller/PhabricatorProjectBoardImportController.php
+++ b/src/applications/project/controller/PhabricatorProjectBoardImportController.php
@@ -94,9 +94,21 @@ final class PhabricatorProjectBoardImportController
       return id(new AphrontRedirectResponse())->setURI($board_uri);
     }
 
+    // Default value. The Tokenizer wants an array of phids.
+    $tokenizer_value = array();
+
+    // Default to the previous milestone, if available.
+    $value_candidate = $this->getPreviousMilestoneIfHasImportableColumns(
+      $viewer, $project);
+
+    if ($value_candidate) {
+      $tokenizer_value[] = $value_candidate->getPHID();
+    }
+
     $proj_selector = id(new AphrontFormTokenizerControl())
       ->setName('importProjectPHID')
       ->setUser($viewer)
+      ->setValue($tokenizer_value)
       ->setDatasource(id(new PhabricatorProjectDatasource())
         ->setParameters(array('mustHaveColumns' => true))
       ->setLimit(1));
@@ -104,10 +116,131 @@ final class PhabricatorProjectBoardImportController
     return $this->newDialog()
       ->setTitle(pht('Import Columns'))
       ->setWidth(AphrontDialogView::WIDTH_FORM)
-      ->appendParagraph(pht('Choose a project to import columns from:'))
+      ->appendParagraph(pht('Choose a project or a milestone to import '.
+        'columns from:'))
       ->appendChild($proj_selector)
       ->addCancelButton($board_uri)
       ->addSubmitButton(pht('Import'));
   }
 
+  /**
+   * Starting from a milestone, get the previous milestone,
+   * but only if it has at least one column that could be imported.
+   * @param  PhabricatorUser $viewer     Current user
+   * @param  PhabricatorProject $project Current milestone with no
+   *                                     workboard yet.
+   *                                     Technically, this parameter
+   *                                     could also be a project,
+   *                                     and projects are silently
+   *                                     rejected if passed here.
+   * @return PhabricatorProject|null     The milestone preceding
+   *                                     your specified milestone,
+   *                                     but only if it has at least
+   *                                     one importable column;
+   *                                     null in any other case.
+   */
+  private function getPreviousMilestoneIfHasImportableColumns(
+    PhabricatorUser $viewer,
+    PhabricatorProject $milestone): ?PhabricatorProject {
+
+    // We can suggest something, only if you are creating workboard
+    // on a milestone.
+    if (!$milestone->isMilestone()) {
+      return null;
+    }
+
+    // Possible design choices:
+    // 1. Suggest the most recent milestone (excluding this specific one).
+    //    CONS: Suggesting the most recent milestone doesn't make much sense,
+    //          when I want to create a workboard from a milestone from
+    //          a year ago.
+    //          Side note: to suggest the 'most recent', we need at least one
+    //          more query to find that number. It needs a "SELECT MAX(n)".
+    // 2. Suggest the precedent milestone.
+    //    PRO: convenient when you already worked on a workboard, and you just
+    //         create an additional milestone; convenient also when you create
+    //         a workboard on a old milestone, so as to maintain the
+    //         workboard structure of that time.
+    //         Side note: finding the previous milestone is also extremely
+    //         easy. We avoid the extra query "SELECT MAX(n)".
+    //
+    // So we go with: 2. Suggest the precedent milestone.
+    $previous_milestone_num = (int)$milestone->getMilestoneNumber();
+    $previous_milestone_num--;
+    if ($previous_milestone_num < 1) {
+      return null;
+    }
+
+    $previous_milestone = $this->getProjectMilestoneFromNumber(
+      $viewer,
+      $milestone->getParentProjectPHID(),
+      $previous_milestone_num);
+
+    if (!$previous_milestone) {
+      return null;
+    }
+
+    // Micro-optimization to avoid querying columns.
+    if (!$previous_milestone->getHasWorkboard()) {
+      return null;
+    }
+
+    // Check if this milestone has at least one
+    // existing column which could be imported, or we can cause the error
+    // 'Source Workboard Has No Columns',
+    // and it would be more confusing than useful.
+    $example_column = $this->getOneImportableProjectColumn(
+      $viewer,
+      $previous_milestone->getPHID());
+
+    if (!$example_column) {
+      return null;
+    }
+
+    return $previous_milestone;
+  }
+
+  /**
+   * Get the milestone of a project from its milestone number.
+   * @param PhabricatorUser $viewer    Current user
+   * @param string          $proj_phid Project PHID
+   * @param int             $number    Milestone number
+   */
+  private function getProjectMilestoneFromNumber(
+    PhabricatorUser $viewer,
+    string $proj_phid, int $number): ?PhabricatorProject {
+
+    $query_proj = new PhabricatorProjectQuery();
+    return $query_proj
+      ->setViewer($viewer)
+      ->withParentProjectPHIDs(array($proj_phid))
+      ->withIsMilestone(true)
+      ->withMilestoneNumberBetween($number, $number)
+      ->executeOne();
+  }
+
+  /**
+   * Get whatever non-proxy column on the workboard,
+   * if existing, except for the default "Backlog" column.
+   * @param  PhabricatorUser               $viewer    Current user
+   * @param  string                        $proj_phid Project PHID
+   * @return PhabricatorProjectColumn|null            Column, or null
+   *                                                  if there are none.
+   */
+  private function getOneImportableProjectColumn(
+    PhabricatorUser $viewer,
+    string $proj_phid): ?PhabricatorProjectColumn {
+
+    // Query one (whatever) project column suitable for the import.
+    // This code is inspired from PhabricatorProjectDatasource,
+    // looking at its parameter 'mustHaveColumns'.
+    $query_columns = new PhabricatorProjectColumnQuery();
+    return $query_columns
+      ->setViewer($viewer)
+      ->withProjectPHIDs(array($proj_phid))
+      ->withIsProxyColumn(false)
+      ->setLimit(1)
+      ->executeOne();
+  }
+
 }