Index: mlir/lib/IR/AsmPrinter.cpp
===================================================================
--- mlir/lib/IR/AsmPrinter.cpp
+++ mlir/lib/IR/AsmPrinter.cpp
@@ -25,6 +25,7 @@
 #include "mlir/IR/OpImplementation.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/IR/SubElementInterfaces.h"
+#include "mlir/IR/Verifier.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
@@ -2885,7 +2886,12 @@
   print(os, state, printerFlags);
 }
 void Operation::print(raw_ostream &os, AsmState &state,
-                      const OpPrintingFlags &flags) {
+                      const OpPrintingFlags &originalFlags) {
+  OpPrintingFlags flags = originalFlags;
+  // First verify the operation. If the operation fails to verify then custom
+  // print functions may fail and we have to use generic operation printing.
+  if (!flags.shouldPrintGenericOpForm() && failed(verify(this)))
+      flags.printGenericOpForm();
   OperationPrinter printer(os, flags, state.getImpl());
   if (!getParent() && !flags.shouldUseLocalScope())
     printer.printTopLevelOperation(this);
@@ -2912,7 +2918,19 @@
   print(os, state);
 }
 void Block::print(raw_ostream &os, AsmState &state) {
-  OperationPrinter(os, /*flags=*/llvm::None, state.getImpl()).print(this);
+  OpPrintingFlags flags;
+  // First verify operations in the block. If an operation fails to verify then
+  // custom print functions may fail and we have to use generic operation
+  // printing.
+  if (!empty()) {
+    for (Operation &op : *this) {
+      if (failed(verify(&op))) {
+        flags.printGenericOpForm();
+        break;
+      }
+    }
+  }
+  OperationPrinter(os, /*flags=*/flags, state.getImpl()).print(this);
 }
 
 void Block::dump() { print(llvm::errs()); }
Index: mlir/lib/IR/Operation.cpp
===================================================================
--- mlir/lib/IR/Operation.cpp
+++ mlir/lib/IR/Operation.cpp
@@ -1097,6 +1097,8 @@
           // Check that any value that is used by an operation is defined in the
           // same region as either an operation result.
           auto *operandRegion = operand.getParentRegion();
+          if (!operandRegion)
+            return op.emitError("operation's operand is unlinked");
           if (!region.isAncestor(operandRegion)) {
             return op.emitOpError("using value defined outside the region")
                        .attachNote(isolatedOp->getLoc())
Index: mlir/test/Conversion/AffineToStandard/lower-affine.mlir
===================================================================
--- mlir/test/Conversion/AffineToStandard/lower-affine.mlir
+++ mlir/test/Conversion/AffineToStandard/lower-affine.mlir
@@ -1,4 +1,5 @@
-// RUN: mlir-opt -lower-affine %s | FileCheck %s
+// `-debug` is used here to check that we don't crash when it's specified.
+// RUN: mlir-opt -lower-affine -debug %s | FileCheck %s
 
 // CHECK-LABEL: func @empty() {
 func @empty() {
Index: mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
===================================================================
--- mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
+++ mlir/test/Conversion/SCFToControlFlow/convert-to-cfg.mlir
@@ -1,4 +1,5 @@
-// RUN: mlir-opt -allow-unregistered-dialect -convert-scf-to-cf %s | FileCheck %s
+// `-debug` is used here to check that we don't crash when it's specified.
+// RUN: mlir-opt -allow-unregistered-dialect -convert-scf-to-cf -debug %s | FileCheck %s
 
 // CHECK-LABEL: func @simple_std_for_loop(%{{.*}}: index, %{{.*}}: index, %{{.*}}: index) {
 //  CHECK-NEXT:  cf.br ^bb1(%{{.*}} : index)