diff --git a/mlir/include/mlir/Transforms/DialectConversion.h b/mlir/include/mlir/Transforms/DialectConversion.h
--- a/mlir/include/mlir/Transforms/DialectConversion.h
+++ b/mlir/include/mlir/Transforms/DialectConversion.h
@@ -497,7 +497,9 @@
 /// hooks.
 class ConversionPatternRewriter final : public PatternRewriter {
 public:
-  ConversionPatternRewriter(MLIRContext *ctx);
+  explicit ConversionPatternRewriter(
+      MLIRContext *ctx,
+      function_ref<void(Diagnostic &)> notifyCallback = nullptr);
   ~ConversionPatternRewriter() override;
 
   /// Apply a signature conversion to the entry block of the given region. This
@@ -905,13 +907,16 @@
 /// operations on success and only pre-existing operations are added to the set.
 /// This method only returns failure if there are unreachable blocks in any of
 /// the regions nested within 'ops'.
-LogicalResult applyAnalysisConversion(ArrayRef<Operation *> ops,
-                                      ConversionTarget &target,
-                                      const FrozenRewritePatternSet &patterns,
-                                      DenseSet<Operation *> &convertedOps);
-LogicalResult applyAnalysisConversion(Operation *op, ConversionTarget &target,
-                                      const FrozenRewritePatternSet &patterns,
-                                      DenseSet<Operation *> &convertedOps);
+LogicalResult applyAnalysisConversion(
+    ArrayRef<Operation *> ops, ConversionTarget &target,
+    const FrozenRewritePatternSet &patterns,
+    DenseSet<Operation *> &convertedOps,
+    function_ref<void(Diagnostic &)> notifyCallback = nullptr);
+LogicalResult applyAnalysisConversion(
+    Operation *op, ConversionTarget &target,
+    const FrozenRewritePatternSet &patterns,
+    DenseSet<Operation *> &convertedOps,
+    function_ref<void(Diagnostic &)> notifyCallback = nullptr);
 } // end namespace mlir
 
 #endif // MLIR_TRANSFORMS_DIALECTCONVERSION_H_
diff --git a/mlir/lib/Transforms/Utils/DialectConversion.cpp b/mlir/lib/Transforms/Utils/DialectConversion.cpp
--- a/mlir/lib/Transforms/Utils/DialectConversion.cpp
+++ b/mlir/lib/Transforms/Utils/DialectConversion.cpp
@@ -850,8 +850,11 @@
 namespace mlir {
 namespace detail {
 struct ConversionPatternRewriterImpl {
-  ConversionPatternRewriterImpl(PatternRewriter &rewriter)
-      : argConverter(rewriter, unresolvedMaterializations) {}
+  explicit ConversionPatternRewriterImpl(
+      PatternRewriter &rewriter,
+      function_ref<void(Diagnostic &)> notifyCallback = nullptr)
+      : argConverter(rewriter, unresolvedMaterializations),
+        notifyCallback(notifyCallback) {}
 
   /// Cleanup and destroy any generated rewrite operations. This method is
   /// invoked when the conversion process fails.
@@ -1003,6 +1006,9 @@
   /// active.
   TypeConverter *currentTypeConverter = nullptr;
 
+  /// This allows the user to collect the match failure message.
+  function_ref<void(Diagnostic &)> notifyCallback;
+
 #ifndef NDEBUG
   /// A set of operations that have pending updates. This tracking isn't
   /// strictly necessary, and is thus only active during debug builds for extra
@@ -1470,11 +1476,12 @@
 
 LogicalResult ConversionPatternRewriterImpl::notifyMatchFailure(
     Location loc, function_ref<void(Diagnostic &)> reasonCallback) {
-  LLVM_DEBUG({
+  if (llvm::DebugFlag || notifyCallback) {
     Diagnostic diag(loc, DiagnosticSeverity::Remark);
     reasonCallback(diag);
     logger.startLine() << "** Failure : " << diag.str() << "\n";
-  });
+    notifyCallback(diag);
+  }
   return failure();
 }
 
@@ -1482,9 +1489,10 @@
 // ConversionPatternRewriter
 //===----------------------------------------------------------------------===//
 
-ConversionPatternRewriter::ConversionPatternRewriter(MLIRContext *ctx)
+ConversionPatternRewriter::ConversionPatternRewriter(
+    MLIRContext *ctx, function_ref<void(Diagnostic &)> notifyCallback)
     : PatternRewriter(ctx),
-      impl(new detail::ConversionPatternRewriterImpl(*this)) {}
+      impl(new detail::ConversionPatternRewriterImpl(*this, notifyCallback)) {}
 ConversionPatternRewriter::~ConversionPatternRewriter() {}
 
 void ConversionPatternRewriter::replaceOpWithIf(
@@ -2332,7 +2340,9 @@
       : opLegalizer(target, patterns), mode(mode), trackedOps(trackedOps) {}
 
   /// Converts the given operations to the conversion target.
-  LogicalResult convertOperations(ArrayRef<Operation *> ops);
+  LogicalResult
+  convertOperations(ArrayRef<Operation *> ops,
+                    function_ref<void(Diagnostic &)> notifyCallback = nullptr);
 
 private:
   /// Converts an operation with the given rewriter.
@@ -2409,7 +2419,9 @@
   return success();
 }
 
-LogicalResult OperationConverter::convertOperations(ArrayRef<Operation *> ops) {
+LogicalResult OperationConverter::convertOperations(
+    ArrayRef<Operation *> ops,
+    function_ref<void(Diagnostic &)> notifyCallback) {
   if (ops.empty())
     return success();
   ConversionTarget &target = opLegalizer.getTarget();
@@ -2425,7 +2437,7 @@
   }
 
   // Convert each operation and discard rewrites on failure.
-  ConversionPatternRewriter rewriter(ops.front()->getContext());
+  ConversionPatternRewriter rewriter(ops.front()->getContext(), notifyCallback);
   ConversionPatternRewriterImpl &rewriterImpl = rewriter.getImpl();
   for (auto *op : toConvert)
     if (failed(convert(rewriter, op)))
@@ -3270,15 +3282,17 @@
 mlir::applyAnalysisConversion(ArrayRef<Operation *> ops,
                               ConversionTarget &target,
                               const FrozenRewritePatternSet &patterns,
-                              DenseSet<Operation *> &convertedOps) {
+                              DenseSet<Operation *> &convertedOps,
+                              function_ref<void(Diagnostic &)> notifyCallback) {
   OperationConverter opConverter(target, patterns, OpConversionMode::Analysis,
                                  &convertedOps);
-  return opConverter.convertOperations(ops);
+  return opConverter.convertOperations(ops, notifyCallback);
 }
 LogicalResult
 mlir::applyAnalysisConversion(Operation *op, ConversionTarget &target,
                               const FrozenRewritePatternSet &patterns,
-                              DenseSet<Operation *> &convertedOps) {
+                              DenseSet<Operation *> &convertedOps,
+                              function_ref<void(Diagnostic &)> notifyCallback) {
   return applyAnalysisConversion(llvm::makeArrayRef(op), target, patterns,
-                                 convertedOps);
+                                 convertedOps, notifyCallback);
 }