diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29073869989..0aa22c6deb0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -530,6 +530,10 @@ option(LLVM_BUILD_EXAMPLES
   "Build the LLVM example programs. If OFF, just generate build targets." OFF)
 option(LLVM_INCLUDE_EXAMPLES "Generate build targets for the LLVM examples" ON)
 
+if(LLVM_BUILD_EXAMPLES)
+  add_definitions(-DBUILD_EXAMPLES)
+endif(LLVM_BUILD_EXAMPLES)
+
 option(LLVM_BUILD_TESTS
   "Build LLVM unit tests. If OFF, just generate build targets." OFF)
 option(LLVM_INCLUDE_TESTS "Generate build targets for the LLVM unit tests." ON)
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index ad99d4c7e31..1fbcbf793b2 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -2,6 +2,7 @@ add_subdirectory(BrainF)
 add_subdirectory(Fibonacci)
 add_subdirectory(HowToUseJIT)
 add_subdirectory(HowToUseLLJIT)
+add_subdirectory(IRTransforms)
 add_subdirectory(LLJITExamples)
 add_subdirectory(Kaleidoscope)
 add_subdirectory(ModuleMaker)
diff --git a/examples/IRTransforms/CMakeLists.txt b/examples/IRTransforms/CMakeLists.txt
new file mode 100644
index 00000000000..bf135b92b20
--- /dev/null
+++ b/examples/IRTransforms/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_llvm_library(ExampleIRTransforms
+  InitializePasses.cpp
+  SimplifyCFG.cpp
+
+  ADDITIONAL_HEADER_DIRS
+
+  DEPENDS
+  intrinsics_gen
+  )
diff --git a/examples/IRTransforms/InitializePasses.cpp b/examples/IRTransforms/InitializePasses.cpp
new file mode 100644
index 00000000000..125180715cd
--- /dev/null
+++ b/examples/IRTransforms/InitializePasses.cpp
@@ -0,0 +1,21 @@
+//===-- InitializePasses.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements implements the initialization hook for the example
+// transforms.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InitializePasses.h"
+#include "llvm/PassRegistry.h"
+
+using namespace llvm;
+
+void initializeExampleIRTransforms(PassRegistry &Registry) {
+  initializeSimplifyCFGLegacyPassPass(Registry);
+}
diff --git a/examples/IRTransforms/InitializePasses.h b/examples/IRTransforms/InitializePasses.h
new file mode 100644
index 00000000000..8b6673d518e
--- /dev/null
+++ b/examples/IRTransforms/InitializePasses.h
@@ -0,0 +1,22 @@
+//===- InitializePasses.h - -------------------------------------*- C++ -*-===//
+//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXAMPLES_IRTRANSFORMS_INITIALIZEPASSES__H
+#define LLVM_EXAMPLES_IRTRANSFORMS_INITIALIZEPASSES__H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+void initializeExampleIRTransforms(PassRegistry &Registry);
+void initializeSimplifyCFGLegacyPassPass(PassRegistry &Registry);
+
+} // end namespace llvm
+
+#endif
diff --git a/examples/IRTransforms/SimplifyCFG.cpp b/examples/IRTransforms/SimplifyCFG.cpp
new file mode 100644
index 00000000000..44bbedf4dc4
--- /dev/null
+++ b/examples/IRTransforms/SimplifyCFG.cpp
@@ -0,0 +1,413 @@
+//===- SimplifyCFG.cpp ----------------------------------------------------===//
+//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the control flow graph (CFG) simplifications
+// presented as part of the 'Getting Started With LLVM: Basics' tutorial at the
+// US LLVM Developers Meeting 2019. It also contains additional material.
+//
+// The current file contains three different CFG simplifications. There are
+// multiple versions of each implementation (e.g. _v1 and _v2), which implement
+// additional functionality (e.g. preserving analysis like the DominatorTree) or
+// use additional utilities to simplify the code (e.g. LLVM's PatternMatch.h).
+// The available simplifications are:
+//  1. Trivially Dead block Removal (removeDeadBlocks_v[1,2]).
+//     This simplifications removes all blocks without predecessors in the CFG
+//     from a function.
+//  2. Conditional Branch Elimination (eliminateCondBranches_v[1,2,3])
+//     This simplification replaces conditional branches with constant integer
+//     conditions with unconditional branches.
+//  3. Single Predecessor Block Merging (mergeIntoSinglePredecessor_v[1,2])
+//     This simplification merges blocks with a single predecessor into the
+//     predecessor, if that block has a single successor.
+//
+// TODOs
+//  * Hook up pass to the new pass manager.
+//  * Preserve LoopInfo.
+//  * Add fixed point iteration to delete all dead blocks
+//  * Add implementation using reachability to discover dead blocks.
+//===----------------------------------------------------------------------===//
+
+#include "SimplifyCFG.h"
+#include "InitializePasses.h"
+#include "llvm/Analysis/DomTreeUpdater.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+using namespace PatternMatch;
+
+enum TutorialVersion { V1, V2, V3 };
+static cl::opt<TutorialVersion>
+    Version("tut-simplifycfg-version", cl::desc("Select tutorial version"),
+            cl::Hidden, cl::ValueOptional, cl::init(V1),
+            cl::values(clEnumValN(V1, "v1", "version 1"),
+                       clEnumValN(V2, "v2", "version 2"),
+                       clEnumValN(V3, "v3", "version 3"),
+                       // Sentinel value for unspecified option.
+                       clEnumValN(V3, "", "")));
+
+#define DEBUG_TYPE "tut-simplifycfg"
+
+// Remove trivially dead blocks. First version, not preserving the
+// DominatorTree.
+static bool removeDeadBlocks_v1(Function &F) {
+  bool Changed = false;
+
+  // Remove trivially dead blocks.
+  for (BasicBlock &BB : make_early_inc_range(F)) {
+    // Skip blocks we know to not be trivially dead. We know a block is
+    // guaranteed to be dead, iff it is neither the entry block nor
+    // has any predecessors.
+    if (&F.getEntryBlock() == &BB || !pred_empty(&BB))
+      continue;
+
+    // Notify successors of BB that BB is going to be removed. This removes
+    // incoming values from BB from PHIs in the successors. Note that this will
+    // not actually remove BB from the predecessor lists of its successors.
+    for (BasicBlock *Succ : successors(&BB))
+      Succ->removePredecessor(&BB);
+    // TODO: Find a better place to put such small variations.
+    // Alternatively, we can update the PHI nodes manually:
+    // for (PHINode &PN : make_early_inc_range(Succ->phis()))
+    //  PN.removeIncomingValue(&BB);
+
+    // Replace all instructions in BB with an undef constant. The block is
+    // unreachable, so the results of the instructions should never get used.
+    while (!BB.empty()) {
+      Instruction &I = BB.back();
+      I.replaceAllUsesWith(UndefValue::get(I.getType()));
+      I.eraseFromParent();
+    }
+
+    // Finally remove the basic block.
+    BB.eraseFromParent();
+    Changed = true;
+  }
+
+  return Changed;
+}
+
+// Remove trivially dead blocks. This is the second version and preserves the
+// dominator tree.
+static bool removeDeadBlocks_v2(Function &F, DominatorTree &DT) {
+  bool Changed = false;
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+  SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+  // Remove trivially dead blocks.
+  for (BasicBlock &BB : make_early_inc_range(F)) {
+    // Skip blocks we know to not be trivially dead. We know a block is
+    // guaranteed to be dead, iff it is neither the entry block nor
+    // has any predecessors.
+    if (&F.getEntryBlock() == &BB || !pred_empty(&BB))
+      continue;
+
+    // Notify successors of BB that BB is going to be removed. This removes
+    // incoming values from BB from PHIs in the successors. Note that this will
+    // not actually remove BB from the predecessor lists of its successors.
+    for (BasicBlock *Succ : successors(&BB)) {
+      Succ->removePredecessor(&BB);
+
+      // Collect updates that need to be applied to the dominator tree.
+      DTUpdates.push_back({DominatorTree::Delete, &BB, Succ});
+    }
+
+    // Remove BB via the DomTreeUpdater. DomTreeUpdater::deleteBB conveniently
+    // removes the instructions in BB as well.
+    DTU.deleteBB(&BB);
+    Changed = true;
+  }
+
+  // Apply updates permissively, to remove duplicates.
+  DTU.applyUpdatesPermissive(DTUpdates);
+
+  return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the first version,
+// which *does not* preserve the dominator tree.
+static bool eliminateCondBranches_v1(Function &F) {
+  bool Changed = false;
+
+  // Eliminate branches with constant conditionals.
+  for (BasicBlock &BB : F) {
+    // Skip blocks without conditional branches as terminators.
+    BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator());
+    if (!BI || !BI->isConditional())
+      continue;
+
+    // Skip blocks with conditional branches without ConstantInt conditions.
+    ConstantInt *CI = dyn_cast<ConstantInt>(BI->getCondition());
+    if (!CI)
+      continue;
+
+    // We use the branch condition (CI), to select the successor we remove:
+    // if CI == 1 (true), we remove the second successor, otherwise the first.
+    BasicBlock *RemovedSucc = BI->getSuccessor(CI->isOne());
+    // Tell RemovedSucc we will remove BB from its predecessors.
+    RemovedSucc->removePredecessor(&BB);
+
+    // Replace the conditional branch with an unconditional one, by creating
+    // a new unconditional branch to the selected successor and removing the
+    // conditional one.
+    BranchInst::Create(BI->getSuccessor(CI->isZero()), BI);
+    BI->eraseFromParent();
+    Changed = true;
+  }
+
+  return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the second
+// version, which *does* preserve the dominator tree.
+static bool eliminateCondBranches_v2(Function &F, DominatorTree &DT) {
+  bool Changed = false;
+
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+  SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+  // Eliminate branches with constant conditionals.
+  for (BasicBlock &BB : F) {
+    // Skip blocks without conditional branches as terminators.
+    BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator());
+    if (!BI || !BI->isConditional())
+      continue;
+
+    // Skip blocks with conditional branches without ConstantInt conditions.
+    ConstantInt *CI = dyn_cast<ConstantInt>(BI->getCondition());
+    if (!CI)
+      continue;
+
+    // We use the branch condition (CI), to select the successor we remove:
+    // if CI == 1 (true), we remove the second successor, otherwise the first.
+    BasicBlock *RemovedSucc = BI->getSuccessor(CI->isOne());
+    // Tell RemovedSucc we will remove BB from its predecessors.
+    RemovedSucc->removePredecessor(&BB);
+
+    // Replace the conditional branch with an unconditional one, by creating
+    // a new unconditional branch to the selected successor and removing the
+    // conditional one.
+    BranchInst *NewBranch =
+        BranchInst::Create(BI->getSuccessor(CI->isZero()), BI);
+    BI->eraseFromParent();
+
+    // Delete the edge between BB and RemovedSucc in the DominatorTree, iff
+    // the conditional branch did not use RemovedSucc as both the true and false
+    // branches.
+    if (NewBranch->getSuccessor(0) != RemovedSucc)
+      DTUpdates.push_back({DominatorTree::Delete, &BB, RemovedSucc});
+    Changed = true;
+  }
+
+  // Apply updates permissively, to remove duplicates.
+  DTU.applyUpdatesPermissive(DTUpdates);
+
+  return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the third
+// version, which uses PatternMatch.h.
+static bool eliminateCondBranches_v3(Function &F, DominatorTree &DT) {
+  bool Changed = false;
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+  SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+  // Eliminate branches with constant conditionals.
+  for (BasicBlock &BB : F) {
+    ConstantInt *CI = nullptr;
+    BasicBlock *TakenSucc, *RemovedSucc;
+    // Check if the terminator is a conditional branch, with constant integer
+    // condition and also capture the successor blocks as TakenSucc and
+    // RemovedSucc.
+    if (!match(BB.getTerminator(),
+               m_Br(m_ConstantInt(CI), m_BasicBlock(TakenSucc),
+                    m_BasicBlock(RemovedSucc))))
+      continue;
+
+    // If the condition is false, swap TakenSucc and RemovedSucc.
+    if (CI->isZero())
+      std::swap(TakenSucc, RemovedSucc);
+
+    // Tell RemovedSucc we will remove BB from its predecessors.
+    RemovedSucc->removePredecessor(&BB);
+
+    // Replace the conditional branch with an unconditional one, by creating
+    // a new unconditional branch to the selected successor and removing the
+    // conditional one.
+
+    BranchInst *NewBranch = BranchInst::Create(TakenSucc, BB.getTerminator());
+    BB.getTerminator()->eraseFromParent();
+
+    // Delete the edge between BB and RemovedSucc in the DominatorTree, iff
+    // the conditional branch did not use RemovedSucc as both the true and false
+    // branches.
+    if (NewBranch->getSuccessor(0) != RemovedSucc)
+      DTUpdates.push_back({DominatorTree::Delete, &BB, RemovedSucc});
+    Changed = true;
+  }
+
+  // Apply updates permissively, to remove duplicates.
+  DTU.applyUpdatesPermissive(DTUpdates);
+  return Changed;
+}
+
+// Merge basic blocks into their single predecessor, if their predecessor has a
+// single successor. This is the first version and does not preserve the
+// DominatorTree.
+static bool mergeIntoSinglePredecessor_v1(Function &F) {
+  bool Changed = false;
+
+  // Merge blocks with single predecessors.
+  for (BasicBlock &BB : make_early_inc_range(F)) {
+    BasicBlock *Pred = BB.getSinglePredecessor();
+    // Make sure  BB has a single predecessor Pred and BB is the single
+    // successor of Pred.
+    if (!Pred || Pred->getSingleSuccessor() != &BB)
+      continue;
+
+    // Do not try to merge self loops. That can happen in dead blocks.
+    if (Pred == &BB)
+      continue;
+
+    // Need to replace it before nuking the branch.
+    BB.replaceAllUsesWith(Pred);
+    // PHI nodes in BB can only have a single incoming value. Remove them.
+    for (PHINode &PN : make_early_inc_range(BB.phis())) {
+      PN.replaceAllUsesWith(PN.getIncomingValue(0));
+      PN.eraseFromParent();
+    }
+    // Move all instructions from BB to Pred.
+    for (Instruction &I : make_early_inc_range(BB))
+      I.moveBefore(Pred->getTerminator());
+
+    // Remove the Pred's terminator (which jumped to BB). BB's terminator
+    // will become Pred's terminator.
+    Pred->getTerminator()->eraseFromParent();
+    BB.eraseFromParent();
+
+    Changed = true;
+  }
+
+  return Changed;
+}
+
+// Merge basic blocks into their single predecessor, if their predecessor has a
+// single successor. This is the second version and does preserve the
+// DominatorTree.
+static bool mergeIntoSinglePredecessor_v2(Function &F, DominatorTree &DT) {
+  bool Changed = false;
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+  SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+  // Merge blocks with single predecessors.
+  for (BasicBlock &BB : make_early_inc_range(F)) {
+    BasicBlock *Pred = BB.getSinglePredecessor();
+    // Make sure  BB has a single predecessor Pred and BB is the single
+    // successor of Pred.
+    if (!Pred || Pred->getSingleSuccessor() != &BB)
+      continue;
+
+    // Do not try to merge self loops. That can happen in dead blocks.
+    if (Pred == &BB)
+      continue;
+
+    // Tell DTU about the changes to the CFG: All edges from BB to its
+    // successors get removed and we add edges between Pred and BB's successors.
+    for (BasicBlock *Succ : successors(&BB)) {
+      DTUpdates.push_back({DominatorTree::Delete, &BB, Succ});
+      DTUpdates.push_back({DominatorTree::Insert, Pred, Succ});
+    }
+    // Also remove the edge between Pred and BB.
+    DTUpdates.push_back({DominatorTree::Delete, Pred, &BB});
+
+    // Need to replace it before nuking the branch.
+    BB.replaceAllUsesWith(Pred);
+    // PHI nodes in BB can only have a single incoming value. Remove them.
+    for (PHINode &PN : make_early_inc_range(BB.phis())) {
+      PN.replaceAllUsesWith(PN.getIncomingValue(0));
+      PN.eraseFromParent();
+    }
+    // Move all instructions from BB to Pred.
+    for (Instruction &I : make_early_inc_range(BB))
+      I.moveBefore(Pred->getTerminator());
+
+    // Remove the Pred's terminator (which jumped to BB). BB's terminator
+    // will become Pred's terminator.
+    Pred->getTerminator()->eraseFromParent();
+    DTU.deleteBB(&BB);
+
+    Changed = true;
+  }
+
+  // Apply updates permissively, to remove duplicates.
+  DTU.applyUpdatesPermissive(DTUpdates);
+  return Changed;
+}
+
+static bool doSimplify_v1(Function &F) {
+  return eliminateCondBranches_v1(F) & mergeIntoSinglePredecessor_v1(F) &
+         removeDeadBlocks_v1(F);
+}
+
+static bool doSimplify_v2(Function &F, DominatorTree &DT) {
+  return eliminateCondBranches_v2(F, DT) &
+         mergeIntoSinglePredecessor_v2(F, DT) & removeDeadBlocks_v2(F, DT);
+}
+
+static bool doSimplify_v3(Function &F, DominatorTree &DT) {
+  return eliminateCondBranches_v3(F, DT) &
+         mergeIntoSinglePredecessor_v2(F, DT) & removeDeadBlocks_v2(F, DT);
+}
+
+namespace {
+struct SimplifyCFGLegacyPass : public FunctionPass {
+  static char ID;
+  SimplifyCFGLegacyPass() : FunctionPass(ID) {
+    initializeSimplifyCFGLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<DominatorTreeWrapperPass>();
+    // Version 1 of the implementation does not preserve the dominator tree.
+    if (Version != V1)
+      AU.addPreserved<DominatorTreeWrapperPass>();
+
+    FunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+
+    switch (Version) {
+    case V1:
+      return doSimplify_v1(F);
+    case V2: {
+      auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+      return doSimplify_v2(F, DT);
+    }
+    case V3: {
+      auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+      return doSimplify_v3(F, DT);
+    }
+    }
+
+    llvm_unreachable("Unsupported version");
+  }
+};
+} // namespace
+
+char SimplifyCFGLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(SimplifyCFGLegacyPass, DEBUG_TYPE,
+                      "Tutorial CFG simplification", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(SimplifyCFGLegacyPass, DEBUG_TYPE,
+                    "Tutorial CFG simplifications", false, false)
diff --git a/examples/IRTransforms/SimplifyCFG.h b/examples/IRTransforms/SimplifyCFG.h
new file mode 100644
index 00000000000..09328afb01d
--- /dev/null
+++ b/examples/IRTransforms/SimplifyCFG.h
@@ -0,0 +1,24 @@
+//===- SimplifyCFG.h - Tutorial SimplifyCFG ---------------------*- C++ -*-===//
+//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
+#define LLVM_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
+
+#include "llvm/Pass.h"
+#include "llvm/PassRegistry.h"
+
+namespace llvm {
+
+FunctionPass *createSimplifyCFGPass();
+
+void initializeSimplifyCFGLegacyPassPass(PassRegistry &);
+
+} // end namespace llvm
+
+#endif // LLVM_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll
new file mode 100644
index 00000000000..faf60f3acdb
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll
@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i8* @simp1(i32 %x) {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 42
+; CHECK-NEXT:    [[ADDR:%.*]] = select i1 [[CMP]], i8* inttoptr (i32 1 to i8*), i8* inttoptr (i32 1 to i8*)
+; CHECK-NEXT:    ret i8* [[ADDR]]
+;
+entry:
+  %cmp = icmp slt i32 %x, 42
+  %addr = select i1 %cmp, i8* blockaddress(@simp1, %bb1), i8* blockaddress(@simp1, %bb2)
+  ret i8* %addr
+
+bb1:
+  ret i8* null
+
+bb2:
+  ret i8* null
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll
new file mode 100644
index 00000000000..cb0f82e3757
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll
@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 10
+;
+entry:
+  br i1 true, label %if.then, label %if.else
+
+if.then:
+  ret i32 10
+
+if.else:
+  ret i32 12
+}
+
+define i32 @simp2() {
+; CHECK-LABEL: @simp2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 200
+;
+entry:
+  br i1 false, label %if.then, label %if.else
+
+if.then:
+  ret i32 99
+
+if.else:
+  ret i32 200
+}
+
+declare void @foo(i64)
+
+define i64 @merge_into_predecessor(i64 %a, i64 %b) {
+; CHECK-LABEL: @merge_into_predecessor(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[R:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    call void @foo(i64 [[R]])
+; CHECK-NEXT:    call void @foo(i64 [[A]])
+; CHECK-NEXT:    ret i64 [[R]]
+;
+entry:
+  br label %bb.next
+
+bb.next:
+  %r = add i64 %a, %b
+  call void @foo(i64 %r)
+  call void @foo(i64 %a)
+  br label %bb.next.next
+
+bb.next.next:
+  ret i64 %r
+}
+
+define i64 @merge_into_predecessor_with_phi(i64 %a, i64 %b, i1 %c) {
+; CHECK-LABEL: @merge_into_predecessor_with_phi(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @foo(i64 [[B:%.*]])
+; CHECK-NEXT:    [[R:%.*]] = add i64 [[A:%.*]], [[B]]
+; CHECK-NEXT:    call void @foo(i64 [[R]])
+; CHECK-NEXT:    call void @foo(i64 [[A]])
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[BB_NEXT_NEXT:%.*]], label [[BB_EXIT:%.*]]
+; CHECK:       bb.next.next:
+; CHECK-NEXT:    br label [[BB_EXIT]]
+; CHECK:       bb.exit:
+; CHECK-NEXT:    [[RET:%.*]] = phi i64 [ [[R]], [[ENTRY:%.*]] ], [ 10, [[BB_NEXT_NEXT]] ]
+; CHECK-NEXT:    ret i64 [[RET]]
+;
+entry:
+  call void @foo(i64 %b)
+  br label %bb.next
+
+bb.next:
+  %r = add i64 %a, %b
+  call void @foo(i64 %r)
+  call void @foo(i64 %a)
+  br i1 %c, label %bb.next.next, label %bb.exit
+
+bb.next.next:
+  br label %bb.exit
+
+bb.exit:
+  %ret = phi i64 [ %r, %bb.next], [ 10, %bb.next.next]
+  ret i64 %ret
+
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll
new file mode 100644
index 00000000000..11b70fa5267
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll
@@ -0,0 +1,109 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @remove_dead_blocks() {
+; CHECK-LABEL: @remove_dead_blocks(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:  }
+;
+entry:
+  ret i32 1
+
+bb.1:
+  ret i32 2
+
+bb.2:
+  ret i32 3
+}
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+; CHECK:       bb.1:
+; CHECK-NEXT:    ret i32 2
+; CHECK-NEXT:  }
+;
+entry:
+  ret i32 1
+
+bb.1:
+  ret i32 2
+
+bb.2:
+  br i1 undef, label %bb.1, label %bb.3
+
+bb.3:
+  ret i32 3
+}
+
+define i32 @remove_dead_block_with_phi() {
+; CHECK-LABEL: @remove_dead_block_with_phi(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB_2:%.*]]
+; CHECK:       bb.2:
+; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:  }
+;
+entry:
+  br label %bb.2
+
+bb.1:
+  br label %bb.2
+
+bb.2:
+  %rv = phi i32 [ 1, %entry ], [ 2, %bb.1 ]
+  ret i32 %rv
+}
+
+define i32 @remove_dead_blocks_remaining_uses(i32 %a) {
+; CHECK-LABEL: @remove_dead_blocks_remaining_uses(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:  }
+;
+entry:
+  ret i32 1
+
+bb.2:
+  ret i32 %res
+
+bb.1:
+  %res = add i32 %a, 10
+  br label %bb.2
+}
+
+define i32 @remove_dead_blocks_remaining_uses2(i32 %a, i1 %cond) {
+; CHECK-LABEL: @remove_dead_blocks_remaining_uses2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+; CHECK:       bb.2:
+; CHECK-NEXT:    [[RES2:%.*]] = add i32 undef, 10
+; CHECK-NEXT:    [[RES3:%.*]] = mul i32 [[RES2]], undef
+; CHECK-NEXT:    ret i32 [[RES3]]
+; CHECK:       bb.3:
+; CHECK-NEXT:    ret i32 undef
+; CHECK-NEXT:  }
+;
+entry:
+  ret i32 1
+
+bb.2:
+  %res2 = add i32 %res, 10
+  %res3 = mul i32 %res2, %res
+  ret i32 %res3
+
+bb.3:
+  br label %bb.4
+
+bb.4:
+  ret i32 %res
+
+bb.1:
+  %res = add i32 %a, 10
+  br i1 %cond, label %bb.2, label %bb.3
+  br label %bb.2
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll
new file mode 100644
index 00000000000..76db503faeb
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll
@@ -0,0 +1,70 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @phi_cond_branch_eliminated() {
+; CHECK-LABEL: @phi_cond_branch_eliminated(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 20
+;
+entry:
+  br i1 true, label %bb.2, label %bb.3
+
+bb.2:
+  br label %bb.3
+
+bb.3:
+  %ret = phi i32 [ 10, %entry ], [ 20, %bb.2 ]
+  ret i32 %ret
+}
+
+define i32 @phi_removed() {
+; CHECK-LABEL: @phi_removed(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB_3:%.*]]
+; CHECK:       bb.3:
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  br i1 false, label %bb.2, label %bb.3
+
+bb.2:
+  %pv = phi i32 [ 10, %entry ]
+  br label %bb.3
+
+bb.3:
+  ret i32 0
+}
+
+define i32 @phi_in_dead_region() {
+; CHECK-LABEL: @phi_in_dead_region(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+;
+entry:
+  ret i32 1
+
+bb.1:
+  br i1 true, label %bb.2, label %bb.3
+
+bb.2:
+  br label %bb.3
+
+bb.3:
+  %ret = phi i32 [ 10, %bb.1 ], [ 20, %bb.2 ]
+  ret i32 %ret
+}
+
+define i32 @phi_in_mergable_blocks() {
+; CHECK-LABEL: @phi_in_mergable_blocks(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 10
+;
+entry:
+  br label %bb.1
+
+bb.1:
+  %pv = phi i32 [ 10, %entry ]
+  ret i32 %pv
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll
new file mode 100644
index 00000000000..82a0e0dac23
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 < %s -S -verify-dom-info | FileCheck %s
+
+; Check that we do not crash when we remove edges multiple times in
+; the DomTreeUpdater.
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 undef, label [[IF_THEN_EPIL:%.*]] [
+; CHECK-NEXT:    i8 32, label [[FOR_INC_EPIL:%.*]]
+; CHECK-NEXT:    i8 46, label [[FOR_INC_EPIL]]
+; CHECK-NEXT:    i8 95, label [[FOR_INC_EPIL]]
+; CHECK-NEXT:    i8 45, label [[FOR_INC_EPIL]]
+; CHECK-NEXT:    i8 126, label [[FOR_INC_EPIL]]
+; CHECK-NEXT:    ]
+; CHECK:       if.then.epil:
+; CHECK-NEXT:    unreachable
+; CHECK:       for.inc.epil:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body.epil
+
+for.body.epil:                                    ; preds = %entry
+  switch i8 undef, label %if.then.epil [
+  i8 32, label %for.inc.epil
+  i8 46, label %for.inc.epil
+  i8 95, label %for.inc.epil
+  i8 45, label %for.inc.epil
+  i8 126, label %for.inc.epil
+  ]
+
+if.then.epil:                                     ; preds = %for.body.epil
+  unreachable
+
+for.inc.epil:                                     ; preds = %for.body.epil, %for.body.epil, %for.body.epil, %for.body.epil, %for.body.epil
+  ret void
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll
new file mode 100644
index 00000000000..b3edd1aa505
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll
@@ -0,0 +1,122 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 < %s -S -verify-dom-info | FileCheck %s
+
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i32 undef, label [[SW_DEFAULT23:%.*]] [
+; CHECK-NEXT:    i32 129, label [[SW_BB:%.*]]
+; CHECK-NEXT:    i32 215, label [[SW_BB1:%.*]]
+; CHECK-NEXT:    i32 117, label [[SW_BB1]]
+; CHECK-NEXT:    i32 207, label [[SW_BB1]]
+; CHECK-NEXT:    i32 158, label [[SW_BB1]]
+; CHECK-NEXT:    i32 94, label [[SW_BB1]]
+; CHECK-NEXT:    i32 219, label [[SW_BB1]]
+; CHECK-NEXT:    i32 88, label [[SW_BB1]]
+; CHECK-NEXT:    i32 168, label [[SW_BB1]]
+; CHECK-NEXT:    i32 295, label [[SW_BB1]]
+; CHECK-NEXT:    i32 294, label [[SW_BB1]]
+; CHECK-NEXT:    i32 296, label [[SW_BB1]]
+; CHECK-NEXT:    i32 67, label [[SW_BB1]]
+; CHECK-NEXT:    i32 293, label [[SW_BB1]]
+; CHECK-NEXT:    i32 382, label [[SW_BB1]]
+; CHECK-NEXT:    i32 335, label [[SW_BB1]]
+; CHECK-NEXT:    i32 393, label [[SW_BB1]]
+; CHECK-NEXT:    i32 415, label [[SW_BB1]]
+; CHECK-NEXT:    i32 400, label [[SW_BB1]]
+; CHECK-NEXT:    i32 383, label [[SW_BB1]]
+; CHECK-NEXT:    i32 421, label [[SW_BB1]]
+; CHECK-NEXT:    i32 422, label [[SW_BB1]]
+; CHECK-NEXT:    i32 302, label [[SW_BB1]]
+; CHECK-NEXT:    i32 303, label [[SW_BB1]]
+; CHECK-NEXT:    i32 304, label [[SW_BB1]]
+; CHECK-NEXT:    i32 420, label [[SW_BB1]]
+; CHECK-NEXT:    i32 401, label [[SW_EPILOG24:%.*]]
+; CHECK-NEXT:    i32 53, label [[SW_BB12:%.*]]
+; CHECK-NEXT:    i32 44, label [[SW_BB12]]
+; CHECK-NEXT:    ]
+; CHECK:       sw.bb:
+; CHECK-NEXT:    unreachable
+; CHECK:       sw.bb1:
+; CHECK-NEXT:    br label [[SW_EPILOG24]]
+; CHECK:       sw.bb12:
+; CHECK-NEXT:    switch i32 undef, label [[SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 47, label [[SW_BB13:%.*]]
+; CHECK-NEXT:    i32 8, label [[SW_BB13]]
+; CHECK-NEXT:    ]
+; CHECK:       sw.bb13:
+; CHECK-NEXT:    unreachable
+; CHECK:       sw.default:
+; CHECK-NEXT:    unreachable
+; CHECK:       sw.default23:
+; CHECK-NEXT:    unreachable
+; CHECK:       sw.epilog24:
+; CHECK-NEXT:    [[PREVIOUS_3:%.*]] = phi i32 [ undef, [[SW_BB1]] ], [ 401, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    unreachable
+;
+entry:
+  br label %while.body
+
+while.body:                                       ; preds = %entry
+  switch i32 undef, label %sw.default23 [
+  i32 129, label %sw.bb
+  i32 215, label %sw.bb1
+  i32 117, label %sw.bb1
+  i32 207, label %sw.bb1
+  i32 158, label %sw.bb1
+  i32 94, label %sw.bb1
+  i32 219, label %sw.bb1
+  i32 88, label %sw.bb1
+  i32 168, label %sw.bb1
+  i32 295, label %sw.bb1
+  i32 294, label %sw.bb1
+  i32 296, label %sw.bb1
+  i32 67, label %sw.bb1
+  i32 293, label %sw.bb1
+  i32 382, label %sw.bb1
+  i32 335, label %sw.bb1
+  i32 393, label %sw.bb1
+  i32 415, label %sw.bb1
+  i32 400, label %sw.bb1
+  i32 383, label %sw.bb1
+  i32 421, label %sw.bb1
+  i32 422, label %sw.bb1
+  i32 302, label %sw.bb1
+  i32 303, label %sw.bb1
+  i32 304, label %sw.bb1
+  i32 420, label %sw.bb1
+  i32 401, label %sw.epilog24
+  i32 53, label %sw.bb12
+  i32 44, label %sw.bb12
+  ]
+
+sw.bb:                                            ; preds = %while.body
+  unreachable
+
+sw.bb1:                                           ; preds = %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body
+  br i1 false, label %land.lhs.true, label %sw.epilog24
+
+land.lhs.true:                                    ; preds = %sw.bb1
+  br label %sw.epilog24
+
+sw.bb12:                                          ; preds = %while.body, %while.body
+  switch i32 undef, label %sw.default [
+  i32 47, label %sw.bb13
+  i32 8, label %sw.bb13
+  ]
+
+sw.bb13:                                          ; preds = %sw.bb12, %sw.bb12
+  unreachable
+
+sw.default:                                       ; preds = %sw.bb12
+  unreachable
+
+sw.default23:                                     ; preds = %while.body
+  unreachable
+
+sw.epilog24:                                      ; preds = %land.lhs.true, %sw.bb1, %while.body
+  %Previous.3 = phi i32 [ undef, %land.lhs.true ], [ undef, %sw.bb1 ], [ 401, %while.body ]
+  unreachable
+}
diff --git a/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll
new file mode 100644
index 00000000000..f9705a6948b
--- /dev/null
+++ b/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll
@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i32 1
+; CHECK:       bb.1:
+; CHECK-NEXT:    br label [[BB_1:%.*]]
+; CHECK:       bb.2:
+; CHECK-NEXT:    [[P:%.*]] = phi i32 [ 0, [[BB_2:%.*]] ]
+; CHECK-NEXT:    br label [[BB_2]]
+;
+entry:
+  ret i32 1
+
+bb.1:
+  br label %bb.1
+
+bb.2:
+  %p = phi i32 [ 0, %bb.2]
+  br label %bb.2
+}
diff --git a/tools/opt/CMakeLists.txt b/tools/opt/CMakeLists.txt
index 4ea9baf447a..90730e324c7 100644
--- a/tools/opt/CMakeLists.txt
+++ b/tools/opt/CMakeLists.txt
@@ -42,3 +42,7 @@ export_executable_symbols(opt)
 if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
   target_link_libraries(opt PRIVATE Polly)
 endif(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
+
+if(LLVM_BUILD_EXAMPLES)
+    target_link_libraries(opt PRIVATE ExampleIRTransforms)
+endif(LLVM_BUILD_EXAMPLES)
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index 1dc5dd448f3..1ad6079f67b 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -476,6 +476,10 @@ static TargetMachine* GetTargetMachine(Triple TheTriple, StringRef CPUStr,
                                         getCodeModel(), GetCodeGenOptLevel());
 }
 
+#ifdef BUILD_EXAMPLES
+void initializeExampleIRTransforms(llvm::PassRegistry &Registry);
+#endif
+
 #ifdef LINK_POLLY_INTO_TOOLS
 namespace polly {
 void initializePollyPasses(llvm::PassRegistry &Registry);
@@ -557,6 +561,10 @@ int main(int argc, char **argv) {
   initializeWriteBitcodePassPass(Registry);
   initializeHardwareLoopsPass(Registry);
 
+#ifdef BUILD_EXAMPLES
+  initializeExampleIRTransforms(Registry);
+#endif
+
 #ifdef LINK_POLLY_INTO_TOOLS
   polly::initializePollyPasses(Registry);
 #endif