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"
@@ -40,6 +41,7 @@
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include "llvm/Support/Threading.h"
 
 #include <tuple>
 
@@ -1245,9 +1247,37 @@
 } // namespace detail
 } // namespace mlir
 
+/// Verifies the operation and switches to generic op printing if verification
+/// fails. We need to do this because custom print functions may fail for
+/// invalid ops.
+static OpPrintingFlags verifyOpAndAdjustFlags(Operation *op,
+                                              OpPrintingFlags printerFlags) {
+  // Protection from infinite recursion: operation verification may want to
+  // print the operation itself, causing this function to be called recursively.
+  thread_local bool alwaysPrintGenericForm = false;
+  if (alwaysPrintGenericForm)
+    return printerFlags.printGenericOpForm();
+
+  if (!printerFlags.shouldPrintGenericOpForm()) {
+    // Ignore errors emitted by the verifier. We check the thread id to avoid
+    // consuming other threads' errors.
+    auto parentThreadId = llvm::get_threadid();
+    ScopedDiagnosticHandler diagHandler(op->getContext(), [&](Diagnostic &) {
+      return success(parentThreadId == llvm::get_threadid());
+    });
+    alwaysPrintGenericForm = true;
+    if (failed(verify(op)))
+      printerFlags.printGenericOpForm();
+    alwaysPrintGenericForm = false;
+  }
+
+  return printerFlags;
+}
+
 AsmState::AsmState(Operation *op, const OpPrintingFlags &printerFlags,
                    LocationMap *locationMap)
-    : impl(std::make_unique<AsmStateImpl>(op, printerFlags, locationMap)) {}
+    : impl(std::make_unique<AsmStateImpl>(
+          op, verifyOpAndAdjustFlags(op, printerFlags), locationMap)) {}
 AsmState::~AsmState() = default;
 
 const OpPrintingFlags &AsmState::getPrinterFlags() const {
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)