diff --git a/llvm/unittests/IR/DominatorTreeBatchUpdatesTest.cpp b/llvm/unittests/IR/DominatorTreeBatchUpdatesTest.cpp
new file mode 100644
index 0000000..4ad1f69
--- /dev/null
+++ b/llvm/unittests/IR/DominatorTreeBatchUpdatesTest.cpp
@@ -0,0 +1,260 @@
+//===- llvm/unittests/IR/DominatorTreeBatchUpdatesTest.cpp ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <random>
+#include "CFGBuilder.h"
+#include "gtest/gtest.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/Support/GenericDomTreeConstruction.h"
+
+#define DEBUG_TYPE "batch-update-tests"
+
+using namespace llvm;
+
+namespace {
+const auto CFGInsert = CFGBuilder::ActionKind::Insert;
+const auto CFGDelete = CFGBuilder::ActionKind::Delete;
+
+struct PostDomTree : PostDomTreeBase<BasicBlock> {
+  PostDomTree(Function &F) { recalculate(F); }
+};
+
+using DomUpdate = DominatorTree::UpdateType;
+static_assert(
+    std::is_same<DomUpdate, PostDomTree::UpdateType>::value,
+    "Trees differing only in IsPostDom should have the same update types");
+using DomSNCA = DomTreeBuilder::SemiNCAInfo<DomTreeBuilder::BBDomTree>;
+using PostDomSNCA = DomTreeBuilder::SemiNCAInfo<DomTreeBuilder::BBPostDomTree>;
+const auto Insert = DominatorTree::Insert;
+const auto Delete = DominatorTree::Delete;
+
+std::vector<DomUpdate> ToDomUpdates(CFGBuilder &B,
+                                    std::vector<CFGBuilder::Update> &In) {
+  std::vector<DomUpdate> Res;
+  Res.reserve(In.size());
+
+  for (const auto &CFGU : In)
+    Res.push_back({CFGU.Action == CFGInsert ? Insert : Delete,
+                   B.getOrAddBlock(CFGU.Edge.From),
+                   B.getOrAddBlock(CFGU.Edge.To)});
+  return Res;
+}
+}  // namespace
+
+TEST(DominatorTreeBatchUpdates, LegalizeDomUpdates) {
+  CFGHolder Holder;
+  CFGBuilder Builder(Holder.F, {{"A", "B"}}, {});
+
+  BasicBlock *A = Builder.getOrAddBlock("A");
+  BasicBlock *B = Builder.getOrAddBlock("B");
+  BasicBlock *C = Builder.getOrAddBlock("C");
+  BasicBlock *D = Builder.getOrAddBlock("D");
+
+  std::vector<DomUpdate> Updates = {
+      {Insert, B, C}, {Insert, C, D}, {Delete, B, C}, {Insert, B, C},
+      {Insert, B, D}, {Delete, C, D}, {Delete, A, B}};
+  SmallVector<DomUpdate, 4> Legalized;
+  DomSNCA::LegalizeUpdates(Updates, Legalized);
+  DEBUG(dbgs() << "Legalized updates:\t");
+  DEBUG(for (auto &U : Legalized) dbgs() << U << ", ");
+  DEBUG(dbgs() << "\n");
+  EXPECT_EQ(Legalized.size(), 3UL);
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Insert, B, C}), Legalized.end());
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Insert, B, D}), Legalized.end());
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Delete, A, B}), Legalized.end());
+}
+
+TEST(DominatorTreeBatchUpdates, LegalizePostDomUpdates) {
+  CFGHolder Holder;
+  CFGBuilder Builder(Holder.F, {{"A", "B"}}, {});
+
+  BasicBlock *A = Builder.getOrAddBlock("A");
+  BasicBlock *B = Builder.getOrAddBlock("B");
+  BasicBlock *C = Builder.getOrAddBlock("C");
+  BasicBlock *D = Builder.getOrAddBlock("D");
+
+  std::vector<DomUpdate> Updates = {
+      {Insert, B, C}, {Insert, C, D}, {Delete, B, C}, {Insert, B, C},
+      {Insert, B, D}, {Delete, C, D}, {Delete, A, B}};
+  SmallVector<DomUpdate, 4> Legalized;
+  PostDomSNCA::LegalizeUpdates(Updates, Legalized);
+  DEBUG(dbgs() << "Legalized postdom updates:\t");
+  DEBUG(for (auto &U : Legalized) dbgs() << U << ", ");
+  DEBUG(dbgs() << "\n");
+  EXPECT_EQ(Legalized.size(), 3UL);
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Insert, C, B}), Legalized.end());
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Insert, D, B}), Legalized.end());
+  EXPECT_NE(llvm::find(Legalized, DomUpdate{Delete, B, A}), Legalized.end());
+}
+
+TEST(DominatorTreeBatchUpdates, SingleInsertion) {
+  CFGHolder Holder;
+  CFGBuilder Builder(Holder.F, {{"A", "B"}}, {{CFGInsert, {"B", "C"}}});
+
+  DominatorTree DT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+  PostDomTree PDT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+
+  BasicBlock *B = Builder.getOrAddBlock("B");
+  BasicBlock *C = Builder.getOrAddBlock("C");
+  std::vector<DomUpdate> Updates = {{Insert, B, C}};
+
+  ASSERT_TRUE(Builder.applyUpdate());
+
+  DT.applyUpdates(Updates);
+  EXPECT_TRUE(DT.verify());
+  PDT.applyUpdates(Updates);
+  EXPECT_TRUE(PDT.verify());
+}
+
+TEST(DominatorTreeBatchUpdates, SingleDeletion) {
+  CFGHolder Holder;
+  CFGBuilder Builder(Holder.F, {{"A", "B"}, {"B", "C"}},
+                     {{CFGDelete, {"B", "C"}}});
+
+  DominatorTree DT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+  PostDomTree PDT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+
+  BasicBlock *B = Builder.getOrAddBlock("B");
+  BasicBlock *C = Builder.getOrAddBlock("C");
+  std::vector<DomUpdate> Updates = {{Delete, B, C}};
+
+  ASSERT_TRUE(Builder.applyUpdate());
+
+  DT.applyUpdates(Updates);
+  EXPECT_TRUE(DT.verify());
+  PDT.applyUpdates(Updates);
+  EXPECT_TRUE(PDT.verify());
+}
+
+TEST(DominatorTreeBatchUpdates, FewInsertion) {
+  std::vector<CFGBuilder::Update> CFGUpdates = {{CFGInsert, {"B", "C"}},
+                                                {CFGInsert, {"C", "B"}},
+                                                {CFGInsert, {"C", "D"}},
+                                                {CFGInsert, {"D", "E"}}};
+
+  CFGHolder Holder;
+  CFGBuilder Builder(Holder.F, {{"A", "B"}}, CFGUpdates);
+
+  DominatorTree DT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+  PostDomTree PDT(*Holder.F);
+  EXPECT_TRUE(PDT.verify());
+
+  BasicBlock *B = Builder.getOrAddBlock("B");
+  BasicBlock *C = Builder.getOrAddBlock("C");
+  BasicBlock *D = Builder.getOrAddBlock("D");
+  BasicBlock *E = Builder.getOrAddBlock("E");
+
+  std::vector<DomUpdate> Updates = {
+      {Insert, B, C}, {Insert, C, B}, {Insert, C, D}, {Insert, D, E}};
+
+  while (Builder.applyUpdate())
+    ;
+
+  DT.applyUpdates(Updates);
+  EXPECT_TRUE(DT.verify());
+  PDT.applyUpdates(Updates);
+  EXPECT_TRUE(PDT.verify());
+}
+
+TEST(DominatorTreeBatchUpdates, FewDeletions) {
+  std::vector<CFGBuilder::Update> CFGUpdates = {{CFGDelete, {"B", "C"}},
+                                                {CFGDelete, {"C", "B"}},
+                                                {CFGDelete, {"B", "D"}},
+                                                {CFGDelete, {"D", "E"}}};
+
+  CFGHolder Holder;
+  CFGBuilder Builder(
+      Holder.F, {{"A", "B"}, {"B", "C"}, {"B", "D"}, {"D", "E"}, {"C", "B"}},
+      CFGUpdates);
+
+  DominatorTree DT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+  PostDomTree PDT(*Holder.F);
+  EXPECT_TRUE(PDT.verify());
+
+  auto Updates = ToDomUpdates(Builder, CFGUpdates);
+
+  while (Builder.applyUpdate())
+    ;
+
+  DT.applyUpdates(Updates);
+  EXPECT_TRUE(DT.verify());
+  PDT.applyUpdates(Updates);
+  EXPECT_TRUE(PDT.verify());
+}
+
+TEST(DominatorTreeBatchUpdates, InsertDelete) {
+  std::vector<CFGBuilder::Arc> Arcs = {
+      {"1", "2"}, {"2", "3"}, {"3", "4"},  {"4", "5"},  {"5", "6"},  {"5", "7"},
+      {"3", "8"}, {"8", "9"}, {"9", "10"}, {"8", "11"}, {"11", "12"}};
+
+  std::vector<CFGBuilder::Update> Updates = {
+      {CFGInsert, {"2", "4"}},  {CFGInsert, {"12", "10"}},
+      {CFGInsert, {"10", "9"}}, {CFGInsert, {"7", "6"}},
+      {CFGInsert, {"7", "5"}},  {CFGDelete, {"3", "8"}},
+      {CFGInsert, {"10", "7"}}, {CFGInsert, {"2", "8"}},
+      {CFGDelete, {"3", "4"}},  {CFGDelete, {"8", "9"}},
+      {CFGDelete, {"11", "12"}}};
+
+  CFGHolder Holder;
+  CFGBuilder B(Holder.F, Arcs, Updates);
+  DominatorTree DT(*Holder.F);
+  EXPECT_TRUE(DT.verify());
+  PostDomTree PDT(*Holder.F);
+  EXPECT_TRUE(PDT.verify());
+
+  while (B.applyUpdate())
+    ;
+
+  auto DomUpdates = ToDomUpdates(B, Updates);
+  DT.applyUpdates(DomUpdates);
+  EXPECT_TRUE(DT.verify());
+  PDT.applyUpdates(DomUpdates);
+  EXPECT_TRUE(PDT.verify());
+}
+
+TEST(DominatorTreeBatchUpdates, InsertDeleteExhaustive) {
+  std::vector<CFGBuilder::Arc> Arcs = {
+      {"1", "2"}, {"2", "3"}, {"3", "4"},  {"4", "5"},  {"5", "6"},  {"5", "7"},
+      {"3", "8"}, {"8", "9"}, {"9", "10"}, {"8", "11"}, {"11", "12"}};
+
+  std::vector<CFGBuilder::Update> Updates = {
+      {CFGInsert, {"2", "4"}},  {CFGInsert, {"12", "10"}},
+      {CFGInsert, {"10", "9"}}, {CFGInsert, {"7", "6"}},
+      {CFGInsert, {"7", "5"}},  {CFGDelete, {"3", "8"}},
+      {CFGInsert, {"10", "7"}}, {CFGInsert, {"2", "8"}},
+      {CFGDelete, {"3", "4"}},  {CFGDelete, {"8", "9"}},
+      {CFGDelete, {"11", "12"}}};
+
+  std::mt19937 Generator(0);
+  for (unsigned i = 0; i < 16; ++i) {
+    std::shuffle(Updates.begin(), Updates.end(), Generator);
+    CFGHolder Holder;
+    CFGBuilder B(Holder.F, Arcs, Updates);
+    DominatorTree DT(*Holder.F);
+    EXPECT_TRUE(DT.verify());
+    PostDomTree PDT(*Holder.F);
+    EXPECT_TRUE(PDT.verify());
+
+    while (B.applyUpdate())
+      ;
+
+    auto DomUpdates = ToDomUpdates(B, Updates);
+    DT.applyUpdates(DomUpdates);
+    EXPECT_TRUE(DT.verify());
+    PDT.applyUpdates(DomUpdates);
+    EXPECT_TRUE(PDT.verify());
+  }
+}