Index: llvm/include/llvm/Passes/StandardInstrumentations.h
===================================================================
--- llvm/include/llvm/Passes/StandardInstrumentations.h
+++ llvm/include/llvm/Passes/StandardInstrumentations.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/IR/PassInstrumentation.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/IR/PassTimingInfo.h"
 
 #include <string>
@@ -73,6 +74,13 @@
   bool DebugLogging;
 };
 
+// Print IR on crash.
+class PrintCrashIRInstrumentation {
+public:
+  PrintCrashIRInstrumentation() {}
+  void registerCallbacks(PassInstrumentationCallbacks &PIC);
+};
+
 /// This class provides an interface to register all the standard pass
 /// instrumentations and manages their state (if any).
 class StandardInstrumentations {
@@ -80,6 +88,7 @@
   PrintPassInstrumentation PrintPass;
   TimePassesHandler TimePasses;
   OptNoneInstrumentation OptNone;
+  PrintCrashIRInstrumentation PrintCrashIR;
 
 public:
   StandardInstrumentations(bool DebugLogging) : PrintPass(DebugLogging) {}
@@ -88,6 +97,7 @@
 
   TimePassesHandler &getTimePasses() { return TimePasses; }
 };
+
 } // namespace llvm
 
 #endif
Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -258,6 +258,18 @@
                             cl::Hidden,
                             cl::desc("Enable inline deferral during PGO"));
 
+// A pass for testing -print-on-crash.
+// DO NOT USE THIS EXCEPT FOR TESTING!
+class TriggerCrashPass : public PassInfoMixin<TriggerCrashPass> {
+public:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM);
+};
+
+// DO NOT USE THIS EXCEPT FOR TESTING!
+PreservedAnalyses TriggerCrashPass::run(Function &, FunctionAnalysisManager &) {
+  __builtin_trap();
+}
+
 PipelineTuningOptions::PipelineTuningOptions() {
   LoopInterleaving = true;
   LoopVectorization = true;
Index: llvm/lib/Passes/PassRegistry.def
===================================================================
--- llvm/lib/Passes/PassRegistry.def
+++ llvm/lib/Passes/PassRegistry.def
@@ -260,6 +260,7 @@
 FUNCTION_PASS("spec-phis", SpeculateAroundPHIsPass())
 FUNCTION_PASS("sroa", SROA())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
+FUNCTION_PASS("trigger-crash", TriggerCrashPass())
 FUNCTION_PASS("vector-combine", VectorCombinePass())
 FUNCTION_PASS("verify", VerifierPass())
 FUNCTION_PASS("verify<domtree>", DominatorTreeVerifierPass())
Index: llvm/lib/Passes/StandardInstrumentations.cpp
===================================================================
--- llvm/lib/Passes/StandardInstrumentations.cpp
+++ llvm/lib/Passes/StandardInstrumentations.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Passes/StandardInstrumentations.h"
 #include "llvm/ADT/Any.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Analysis/CallGraphSCCPass.h"
 #include "llvm/Analysis/LazyCallGraph.h"
 #include "llvm/Analysis/LoopInfo.h"
@@ -23,8 +24,10 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassInstrumentation.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
 #include <vector>
 
@@ -43,6 +46,14 @@
                    cl::desc("Print all pass management debugging information. "
                             "`-debug-pass-manager` must also be specified"));
 
+// A hidden option to print the IR that was being processed when a pass
+// crashes.  Note that nothing will be output if there is no crash.  This
+// option is affected by the -print-module-scope option.
+static cl::opt<bool>
+    PrintCrashIR("print-on-crash",
+                 cl::desc("Print the last form of the IR before crash"),
+                 cl::init(false), cl::Hidden);
+
 namespace {
 
 /// Extracting Module out of \p IR unit. Also fills a textual description
@@ -189,6 +200,15 @@
   llvm_unreachable("Unknown wrapped IR type");
 }
 
+// The saved IR for the print-on-crash option.  If there are multiple
+// pass managers saving IRs, they will all use this same one so the
+// last saved IR will win.  This is acceptable as it is a debugging tool
+// for a situation that will (hopefully) rarely happen...
+std::string SavedIR = "*** Dump of IR Before Last Pass Unknown ***";
+
+// Crash handler registered when print-on-crash is specified.
+void crashedIRReporter(void *) { dbgs() << SavedIR; }
+
 } // namespace
 
 PrintIRInstrumentation::~PrintIRInstrumentation() {
@@ -338,10 +358,36 @@
   });
 }
 
+void PrintCrashIRInstrumentation::registerCallbacks(
+    PassInstrumentationCallbacks &PIC) {
+  if (!PrintCrashIR)
+    return;
+
+  // Not thread-safe but neither is much of llvm and this is intended
+  // for developer debugging so this is acceptable
+  static bool HandlerRegistered = false;
+  if (HandlerRegistered)
+    return;
+  HandlerRegistered = true;
+
+  sys::AddSignalHandler(crashedIRReporter, nullptr);
+
+  PIC.registerBeforePassCallback([](StringRef PassID, Any IR) {
+    SavedIR.clear();
+    SmallString<80> Banner =
+        formatv("*** Dump of {0}IR Before Last Pass {1} Started ***",
+                llvm::forcePrintModuleIR() ? "Module " : "", PassID);
+    raw_string_ostream OS(SavedIR);
+    unwrapAndPrint(OS, IR, Banner, llvm::forcePrintModuleIR());
+    return true;
+  });
+}
+
 void StandardInstrumentations::registerCallbacks(
     PassInstrumentationCallbacks &PIC) {
   PrintIR.registerCallbacks(PIC);
   PrintPass.registerCallbacks(PIC);
   TimePasses.registerCallbacks(PIC);
   OptNone.registerCallbacks(PIC);
+  PrintCrashIR.registerCallbacks(PIC);
 }
Index: llvm/test/Other/print-on-crash.ll
===================================================================
--- /dev/null
+++ llvm/test/Other/print-on-crash.ll
@@ -0,0 +1,23 @@
+; A test that the hidden option -print-on-crash properly sets a signal handler
+; which gets called when a pass crashes.  The trigger-crash pass calls
+; __builtin_trap.
+
+; RUN: (opt -print-on-crash -passes=trigger-crash || true) < %s 2>&1 | FileCheck %s --check-prefix=CHECK1
+
+; A test that the signal handler set by the  hidden option -print-on-crash
+; is not called when no pass crashes.
+
+; RUN: opt -print-on-crash -passes="default<O2>" < %s 2>&1 | FileCheck %s --check-prefix=CHECK2
+
+; The input corresponds to "int main() { return 0; }" but is irrelevant.
+
+; CHECK1: *** Dump of IR Before Last Pass TriggerCrashPass Started ***
+; CHECK2-NOT: *** Dump of IR Before Last Pass TriggerCrashPass Started ***
+
+define dso_local signext i32 @main() #0 {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  ret i32 0
+}
+