diff --git a/mlir/lib/IR/Builders.cpp b/mlir/lib/IR/Builders.cpp
--- a/mlir/lib/IR/Builders.cpp
+++ b/mlir/lib/IR/Builders.cpp
@@ -519,14 +519,21 @@
   Operation *newOp = op.clone(mapper);
   // The `insert` call below handles the notification for inserting `newOp`
   // itself. But if `newOp` has any regions, we need to notify the listener
-  // about any ops that got inserted inside those regions as part of cloning.
+  // about any ops/blocks that got inserted inside those regions as part of
+  // cloning.
   if (listener) {
-    auto walkFn = [&](Operation *walkedOp) {
-      // TODO: Notify listener of block creation.
-      listener->notifyOperationInserted(walkedOp);
+    std::function<void(Operation *)> walkAndNotify = [&](Operation *op) {
+      for (Region &region : op->getRegions()) {
+        for (Block &block : region) {
+          listener->notifyBlockCreated(&block);
+          for (Operation &op : block)
+            walkAndNotify(&op);
+        }
+      }
+      if (op != newOp)
+        listener->notifyOperationInserted(op);
     };
-    for (Region &region : newOp->getRegions())
-      region.walk(walkFn);
+    walkAndNotify(newOp);
   }
   return insert(newOp);
 }
diff --git a/mlir/lib/IR/PatternMatch.cpp b/mlir/lib/IR/PatternMatch.cpp
--- a/mlir/lib/IR/PatternMatch.cpp
+++ b/mlir/lib/IR/PatternMatch.cpp
@@ -383,9 +383,16 @@
   if (Listener *listener = getListener()) {
     Region::iterator it = mapping.lookup(&region.front())->getIterator();
     while (it != before) {
-      // TODO: Notify listener of nested blocks.
-      it->walk([&](Operation *op) { listener->notifyOperationInserted(op); });
-      it++;
+      std::function<void(Block &)> walkAndNotify = [&](Block &block) {
+        listener->notifyBlockCreated(&block);
+        for (Operation &op : block) {
+          for (Region &region : op.getRegions())
+            for (Block &block : region)
+              walkAndNotify(block);
+          listener->notifyOperationInserted(&op);
+        }
+      };
+      walkAndNotify(*it++);
     }
   }
 }