Index: llvm/lib/AsmParser/LLParser.cpp
===================================================================
--- llvm/lib/AsmParser/LLParser.cpp
+++ llvm/lib/AsmParser/LLParser.cpp
@@ -6979,21 +6979,19 @@
   Type *Ty = nullptr;  LocTy TypeLoc;
   Value *Op0, *Op1;
 
-  if (parseType(Ty, TypeLoc) ||
-      parseToken(lltok::lsquare, "expected '[' in phi value list") ||
-      parseValue(Ty, Op0, PFS) ||
-      parseToken(lltok::comma, "expected ',' after insertelement value") ||
-      parseValue(Type::getLabelTy(Context), Op1, PFS) ||
-      parseToken(lltok::rsquare, "expected ']' in phi value list"))
+  if (parseType(Ty, TypeLoc))
     return true;
 
+  bool First = true;
   bool AteExtraComma = false;
   SmallVector<std::pair<Value*, BasicBlock*>, 16> PHIVals;
 
   while (true) {
-    PHIVals.push_back(std::make_pair(Op0, cast<BasicBlock>(Op1)));
-
-    if (!EatIfPresent(lltok::comma))
+    if (First) {
+      if (Lex.getKind() != lltok::lsquare)
+        break;
+      First = false;
+    } else if (!EatIfPresent(lltok::comma))
       break;
 
     if (Lex.getKind() == lltok::MetadataVar) {
@@ -7007,6 +7005,8 @@
         parseValue(Type::getLabelTy(Context), Op1, PFS) ||
         parseToken(lltok::rsquare, "expected ']' in phi value list"))
       return true;
+
+    PHIVals.push_back(std::make_pair(Op0, cast<BasicBlock>(Op1)));
   }
 
   if (!Ty->isFirstClassType())
Index: llvm/test/Assembler/zero-input-phi.ll
===================================================================
--- /dev/null
+++ llvm/test/Assembler/zero-input-phi.ll
@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S < %s | FileCheck %s
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+define void @dead_phi() {
+; CHECK-LABEL: @dead_phi(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret void
+; CHECK:       return:
+; CHECK-NEXT:    [[R:%.*]] = phi i32
+; CHECK-NEXT:    ret void
+;
+entry:
+  ret void
+
+return:
+  %r = phi i32
+  ret void
+}
Index: llvm/unittests/IR/BasicBlockTest.cpp
===================================================================
--- llvm/unittests/IR/BasicBlockTest.cpp
+++ llvm/unittests/IR/BasicBlockTest.cpp
@@ -169,23 +169,6 @@
   EXPECT_FALSE(Ret->comesBefore(Ret));
 }
 
-TEST(BasicBlockTest, EmptyPhi) {
-  LLVMContext Ctx;
-
-  Module *M = new Module("MyModule", Ctx);
-  FunctionType *FT = FunctionType::get(Type::getVoidTy(Ctx), {}, false);
-  Function *F = Function::Create(FT, Function::ExternalLinkage, "", M);
-
-  BasicBlock *BB1 = BasicBlock::Create(Ctx, "", F);
-  ReturnInst::Create(Ctx, BB1);
-
-  Type *Ty = Type::getInt32PtrTy(Ctx);
-  BasicBlock *BB2 = BasicBlock::Create(Ctx, "", F);
-  PHINode::Create(Ty, 0, "", BB2);
-  ReturnInst::Create(Ctx, BB2);
-  EXPECT_FALSE(verifyModule(*M, &errs()));
-}
-
 class InstrOrderInvalidationTest : public ::testing::Test {
 protected:
   void SetUp() override {