diff --git a/mlir/lib/Transforms/Canonicalizer.cpp b/mlir/lib/Transforms/Canonicalizer.cpp
--- a/mlir/lib/Transforms/Canonicalizer.cpp
+++ b/mlir/lib/Transforms/Canonicalizer.cpp
@@ -27,9 +27,12 @@
 /// Canonicalize operations in nested regions.
 struct Canonicalizer : public impl::CanonicalizerBase<Canonicalizer> {
   Canonicalizer() = default;
+  Canonicalizer(const Canonicalizer &other)
+      : config(other.config), patterns(other.patterns) {}
   Canonicalizer(const GreedyRewriteConfig &config,
                 ArrayRef<std::string> disabledPatterns,
-                ArrayRef<std::string> enabledPatterns) {
+                ArrayRef<std::string> enabledPatterns)
+      : config(config) {
     this->topDownProcessingEnabled = config.useTopDownTraversal;
     this->enableRegionSimplification = config.enableRegionSimplification;
     this->maxIterations = config.maxIterations;
@@ -41,30 +44,31 @@
   /// Initialize the canonicalizer by building the set of patterns used during
   /// execution.
   LogicalResult initialize(MLIRContext *context) override {
+    // Set the config from possible pass options set in the meantime.
+    config.useTopDownTraversal = topDownProcessingEnabled;
+    config.enableRegionSimplification = enableRegionSimplification;
+    config.maxIterations = maxIterations;
+    config.maxNumRewrites = maxNumRewrites;
+
     RewritePatternSet owningPatterns(context);
     for (auto *dialect : context->getLoadedDialects())
       dialect->getCanonicalizationPatterns(owningPatterns);
     for (RegisteredOperationName op : context->getRegisteredOperations())
       op.getCanonicalizationPatterns(owningPatterns, context);
 
-    patterns = FrozenRewritePatternSet(std::move(owningPatterns),
-                                       disabledPatterns, enabledPatterns);
+    patterns = std::make_shared<FrozenRewritePatternSet>(
+        std::move(owningPatterns), disabledPatterns, enabledPatterns);
     return success();
   }
   void runOnOperation() override {
-    GreedyRewriteConfig config;
-    config.useTopDownTraversal = topDownProcessingEnabled;
-    config.enableRegionSimplification = enableRegionSimplification;
-    config.maxIterations = maxIterations;
-    config.maxNumRewrites = maxNumRewrites;
     LogicalResult converged =
-        applyPatternsAndFoldGreedily(getOperation(), patterns, config);
+        applyPatternsAndFoldGreedily(getOperation(), *patterns, config);
     // Canonicalization is best-effort. Non-convergence is not a pass failure.
     if (testConvergence && failed(converged))
       signalPassFailure();
   }
-
-  FrozenRewritePatternSet patterns;
+  GreedyRewriteConfig config;
+  std::shared_ptr<const FrozenRewritePatternSet> patterns;
 };
 } // namespace