Index: lib/IR/AsmWriter.cpp
===================================================================
--- lib/IR/AsmWriter.cpp
+++ lib/IR/AsmWriter.cpp
@@ -3148,7 +3148,7 @@
   if (MDs.empty())
     return;
 
-  if (MDNames.empty())
+  if (TheModule && MDNames.empty())
     TheModule->getMDKindNames(MDNames);
 
   for (const auto &I : MDs) {
Index: unittests/IR/AsmWriterTest.cpp
===================================================================
--- /dev/null
+++ unittests/IR/AsmWriterTest.cpp
@@ -0,0 +1,37 @@
+//===- llvm/unittest/IR/AsmWriter.cpp - AsmWriter tests -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/Module.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(AsmWriterTest, DebugPrintDetachedInstruction) {
+
+  // PR24852: Ensure that an instruction can be printed even when it
+  // has no parent.
+  LLVMContext Ctx;
+  auto Ty = Type::getInt32Ty(Ctx);
+  auto Undef = UndefValue::get(Ty);
+  std::unique_ptr<BinaryOperator> Add(BinaryOperator::CreateAdd(Undef, Undef));
+  Add->setMetadata(
+      "", MDNode::get(Ctx, {ConstantAsMetadata::get(ConstantInt::get(Ty, 1))}));
+  std::string S;
+  raw_string_ostream OS(S);
+  Add->print(OS);
+  std::size_t r = OS.str().find("<badref> = add i32 undef, undef, !<unknown");
+  EXPECT_TRUE(r != std::string::npos);
+}
+
+}
Index: unittests/IR/CMakeLists.txt
===================================================================
--- unittests/IR/CMakeLists.txt
+++ unittests/IR/CMakeLists.txt
@@ -6,6 +6,7 @@
   )
 
 set(IRSources
+  AsmWriterTest.cpp
   AttributesTest.cpp
   ConstantRangeTest.cpp
   ConstantsTest.cpp