diff --git a/toonz/sources/toonz/cellselection.cpp b/toonz/sources/toonz/cellselection.cpp
index 77f3109..381e800 100644
--- a/toonz/sources/toonz/cellselection.cpp
+++ b/toonz/sources/toonz/cellselection.cpp
@@ -1210,6 +1210,47 @@ public:
 };
 
 //-----------------------------------------------------------------------------
+
+class FillEmptyCellUndo final : public TUndo {
+  TCellSelection *m_selection;
+  TXshCell m_cell;
+
+public:
+  FillEmptyCellUndo(int r0, int r1, int c, TXshCell &cell) : m_cell(cell) {
+    m_selection = new TCellSelection();
+    m_selection->selectCells(r0, c, r1, c);
+  }
+
+  ~FillEmptyCellUndo() { delete m_selection; }
+
+  void undo() const override {
+    int r0, c0, r1, c1;
+    m_selection->getSelectedCells(r0, c0, r1, c1);
+    TXsheet *xsh = TApp::instance()->getCurrentXsheet()->getXsheet();
+    for (int c = c0; c <= c1; c++) {
+      xsh->clearCells(r0, c, r1 - r0 + 1);
+    }
+    TApp::instance()->getCurrentXsheet()->notifyXsheetChanged();
+  }
+
+  void redo() const override {
+    int r0, c0, r1, c1;
+    m_selection->getSelectedCells(r0, c0, r1, c1);
+    TXsheet *xsh = TApp::instance()->getCurrentXsheet()->getXsheet();
+    for (int i = r0; i <= r1; i++) xsh->setCell(i, c0, m_cell);
+    TApp::instance()->getCurrentXsheet()->notifyXsheetChanged();
+  }
+
+  int getSize() const override { return sizeof(*this); }
+
+  QString getHistoryString() override {
+    return QObject::tr("Fill In Empty Cells");
+  }
+
+  int getHistoryType() override { return HistoryType::Xsheet; }
+  //-----------------------------------------------------------------------------
+};
+
 }  // namespace
 //-----------------------------------------------------------------------------
 
@@ -1281,6 +1322,7 @@ void TCellSelection::enableCommands() {
 
   enableCommand(this, MI_PasteInto, &TCellSelection::overWritePasteCells);
 
+  enableCommand(this, MI_FillEmptyCell, &TCellSelection::fillEmptyCell);
   enableCommand(this, MI_Reframe1, &TCellSelection::reframe1Cells);
   enableCommand(this, MI_Reframe2, &TCellSelection::reframe2Cells);
   enableCommand(this, MI_Reframe3, &TCellSelection::reframe3Cells);
@@ -1333,7 +1375,8 @@ bool TCellSelection::isEnabledCommand(
                                         MI_Redo,
                                         MI_PasteNumbers,
                                         MI_ConvertToToonzRaster,
-                                        MI_ConvertVectorToVector};
+                                        MI_ConvertVectorToVector,
+                                        MI_FillEmptyCell};
   return commands.contains(commandId);
 }
 
@@ -2785,4 +2828,65 @@ void TCellSelection::convertVectortoVector() {
 
   app->getCurrentTool()->onImageChanged(
       (TImage::Type)app->getCurrentImageType());
+}
+
+void TCellSelection::fillEmptyCell() {
+  if (isEmpty()) return;
+
+  // set up basics
+  bool initUndo = false;
+  TXsheet *xsh  = TApp::instance()->getCurrentXsheet()->getXsheet();
+  int r, r0, c0, c, r1, c1;
+
+  getSelectedCells(r0, c0, r1, c1);
+
+  for (c = c0; c <= c1; c++) {
+    TXshColumn *column = xsh->getColumn(c);
+    if (!column || column->isEmpty() || column->isLocked() ||
+        column->getSoundColumn())
+      continue;
+
+    for (r = r1; r >= r0; r--) {
+      int fillCount = 0;
+      TXshCell cell = xsh->getCell(r, c);
+
+      if (cell.isEmpty()) fillCount++;
+
+      int prevR = r - 1;
+      while (prevR >= 0) {
+        cell = xsh->getCell(prevR, c);
+        if (!cell.isEmpty()) break;
+
+        prevR--;
+        fillCount++;
+      }
+
+      // We've gone past the beginning of timeline without finding a cell.
+      // Do nothing, and end current column processing immediately.
+      if (prevR < 0) break;
+
+      // Adjacent cell is filled.  Move to next one.
+      if (!fillCount) continue;
+
+      // Ok, time fill
+      int startR = prevR + 1;
+      int endR   = startR + fillCount - 1;
+
+      if (!initUndo) {
+        initUndo = true;
+        TUndoManager::manager()->beginBlock();
+      }
+
+      FillEmptyCellUndo *undo = new FillEmptyCellUndo(startR, endR, c, cell);
+      TUndoManager::manager()->add(undo);
+      undo->redo();
+
+      // Let's skip cells we just filled
+      r = prevR;
+    }
+  }
+
+  if (initUndo) TUndoManager::manager()->endBlock();
+
+  TApp::instance()->getCurrentXsheet()->notifyXsheetChanged();
 }
\ No newline at end of file
diff --git a/toonz/sources/toonz/cellselection.h b/toonz/sources/toonz/cellselection.h
index dad866c..6adf8d2 100644
--- a/toonz/sources/toonz/cellselection.h
+++ b/toonz/sources/toonz/cellselection.h
@@ -115,6 +115,8 @@ public:
   void renameMultiCells(QList<TXshCell> &cells);
 
   static bool isEnabledCommand(std::string commandId);
+
+  void fillEmptyCell();
 };
 
 #endif  // TCELLSELECTION_H
diff --git a/toonz/sources/toonz/mainwindow.cpp b/toonz/sources/toonz/mainwindow.cpp
index 46a04d3..ac6f2cb 100644
--- a/toonz/sources/toonz/mainwindow.cpp
+++ b/toonz/sources/toonz/mainwindow.cpp
@@ -1899,6 +1899,7 @@ void MainWindow::defineActions() {
                         tr("Reframe with Empty Inbetweens..."), "");
   createMenuCellsAction(MI_AutoInputCellNumber, tr("Auto Input Cell Number..."),
                         "");
+  createMenuCellsAction(MI_FillEmptyCell, tr("&Fill In Empty Cells"), "");
 
   createRightClickMenuAction(MI_SetKeyframes, tr("&Set Key"), "Z");
   createRightClickMenuAction(MI_PasteNumbers, tr("&Paste Numbers"), "");
diff --git a/toonz/sources/toonz/menubar.cpp b/toonz/sources/toonz/menubar.cpp
index 2de2024..a353626 100644
--- a/toonz/sources/toonz/menubar.cpp
+++ b/toonz/sources/toonz/menubar.cpp
@@ -1285,6 +1285,7 @@ QMenuBar *StackedMenuBar::createFullMenuBar() {
   addMenuItem(cellsMenu, MI_Rollup);
   addMenuItem(cellsMenu, MI_Rolldown);
   addMenuItem(cellsMenu, MI_TimeStretch);
+  addMenuItem(cellsMenu, MI_FillEmptyCell);
   cellsMenu->addSeparator();
   addMenuItem(cellsMenu, MI_DrawingSubForward);
   addMenuItem(cellsMenu, MI_DrawingSubBackward);
diff --git a/toonz/sources/toonz/menubarcommandids.h b/toonz/sources/toonz/menubarcommandids.h
index 92e4dc4..9b2bf5d 100644
--- a/toonz/sources/toonz/menubarcommandids.h
+++ b/toonz/sources/toonz/menubarcommandids.h
@@ -146,6 +146,7 @@
 
 #define MI_PasteNew "MI_PasteNew"
 #define MI_Autorenumber "MI_Autorenumber"
+#define MI_FillEmptyCell "MI_FillEmptyCell"
 
 #define MI_MergeFrames "MI_MergeFrames"
 #define MI_Reverse "MI_Reverse"
diff --git a/toonz/sources/toonz/xshcellviewer.cpp b/toonz/sources/toonz/xshcellviewer.cpp
index 1abe4a9..5508a4a 100644
--- a/toonz/sources/toonz/xshcellviewer.cpp
+++ b/toonz/sources/toonz/xshcellviewer.cpp
@@ -3033,6 +3033,7 @@ void CellArea::createCellMenu(QMenu &menu, bool isCellSelected) {
             cmdManager->getAction(MI_AutoInputCellNumber));
       }
       menu.addMenu(editCellNumbersMenu);
+      menu.addAction(cmdManager->getAction(MI_FillEmptyCell));
 
       menu.addSeparator();
       menu.addAction(cmdManager->getAction(MI_Autorenumber));
@@ -3130,6 +3131,8 @@ void CellArea::createCellMenu(QMenu &menu, bool isCellSelected) {
         (TApp::instance()->getCurrentLevel()->getLevel() &&
          TApp::instance()->getCurrentLevel()->getLevel()->getChildLevel()))
       menu.addAction(cmdManager->getAction(MI_LipSyncPopup));
+  } else {
+    menu.addAction(cmdManager->getAction(MI_FillEmptyCell));
   }
   menu.addSeparator();
   if (!soundCellsSelected)