diff --git a/mlir/include/mlir/IR/PatternMatch.h b/mlir/include/mlir/IR/PatternMatch.h
--- a/mlir/include/mlir/IR/PatternMatch.h
+++ b/mlir/include/mlir/IR/PatternMatch.h
@@ -546,9 +546,9 @@
   /// they would like to be notified about certain types of mutations.
 
   /// Notify the rewriter that the specified operation is about to be replaced
-  /// with another set of operations. This is called before the uses of the
-  /// operation have been changed.
-  virtual void notifyRootReplaced(Operation *op) {}
+  /// with the set of values potentially produced by new operations. This is
+  /// called before the uses of the operation have been changed.
+  virtual void notifyRootReplaced(Operation *op, ValueRange replacement) {}
 
   /// This is called on an operation that a rewrite is removing, right before
   /// the operation is deleted. At this point, the operation has zero uses.
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
@@ -216,7 +216,7 @@
          "incorrect number of values to replace operation");
 
   // Notify the rewriter subclass that we're about to replace this root.
-  notifyRootReplaced(op);
+  notifyRootReplaced(op, newValues);
 
   // Replace each use of the results when the functor is true.
   bool replacedAllUses = true;
@@ -244,7 +244,7 @@
 /// the operation.
 void RewriterBase::replaceOp(Operation *op, ValueRange newValues) {
   // Notify the rewriter subclass that we're about to replace this root.
-  notifyRootReplaced(op);
+  notifyRootReplaced(op, newValues);
 
   assert(op->getNumResults() == newValues.size() &&
          "incorrect # of replacement values");
diff --git a/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp b/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
--- a/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
+++ b/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
@@ -69,7 +69,7 @@
   // When the root of a pattern is about to be replaced, it can trigger
   // simplifications to its users - make sure to add them to the worklist
   // before the root is changed.
-  void notifyRootReplaced(Operation *op) override;
+  void notifyRootReplaced(Operation *op, ValueRange replacement) override;
 
   /// PatternRewriter hook for erasing a dead operation.
   void eraseOp(Operation *op) override;
@@ -348,7 +348,8 @@
   });
 }
 
-void GreedyPatternRewriteDriver::notifyRootReplaced(Operation *op) {
+void GreedyPatternRewriteDriver::notifyRootReplaced(Operation *op,
+                                                    ValueRange replacement) {
   LLVM_DEBUG({
     logger.startLine() << "** Replace : '" << op->getName() << "'(" << op
                        << ")\n";
@@ -437,7 +438,7 @@
 
   // When a root is going to be replaced, its removal will be notified as well.
   // So there is nothing to do here.
-  void notifyRootReplaced(Operation *op) override {}
+  void notifyRootReplaced(Operation *op, ValueRange replacement) override {}
 
 private:
   /// The low-level pattern applicator.