diff --git a/include/llvm/Bitcode/ReaderWriter.h b/include/llvm/Bitcode/ReaderWriter.h
index b32009d38e9..6fb77565979 100644
--- a/include/llvm/Bitcode/ReaderWriter.h
+++ b/include/llvm/Bitcode/ReaderWriter.h
@@ -160,6 +160,7 @@ namespace llvm {
     InvalidMultipleBlocks, // We found multiple blocks of a kind that should
                            // have only one
     NeverResolvedValueFoundInFunction,
+    NeverResolvedFunctionFromBlockAddress,
     InvalidValue // Invalid version, inst number, attr number, etc
   };
   inline std::error_code make_error_code(BitcodeError E) {
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 9dd209df124..8537354a5b3 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -31,11 +31,31 @@ enum {
   SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
 };
 
-void BitcodeReader::materializeForwardReferencedFunctions() {
+std::error_code BitcodeReader::materializeForwardReferencedFunctions() {
+  if (WillMaterializeAllForwardRefs)
+    return std::error_code();
+
+  // Prevent recursion.
+  WillMaterializeAllForwardRefs = true;
+
   while (!BlockAddrFwdRefs.empty()) {
     Function *F = BlockAddrFwdRefs.begin()->first;
-    F->Materialize();
+    assert(F && "Expected valid function");
+    // Check for a function that isn't materializable to prevent an infinite
+    // loop.  When parsing a blockaddress stored in a global variable, there
+    // isn't a trivial way to check if a function will have a body without a
+    // linear search through FunctionsWithBodies, so just check it here.
+    if (!F->isMaterializable())
+      return Error(BitcodeError::NeverResolvedFunctionFromBlockAddress);
+
+    // Try to materialize F.
+    if (std::error_code EC = Materialize(F))
+      return EC;
   }
+
+  // Reset state.
+  WillMaterializeAllForwardRefs = false;
+  return std::error_code();
 }
 
 void BitcodeReader::FreeState() {
@@ -1587,6 +1607,9 @@ std::error_code BitcodeReader::ParseConstants() {
       if (!Fn)
         return Error(BitcodeError::InvalidRecord);
 
+      // Don't let Fn get dematerialized.
+      BlockAddressesTaken.insert(Fn);
+
       // If the function is already parsed we can insert the block address right
       // away.
       if (!Fn->empty()) {
@@ -3274,13 +3297,21 @@ std::error_code BitcodeReader::Materialize(GlobalValue *GV) {
     }
   }
 
-  return std::error_code();
+  // Bring in any functions that this function forward-referenced via
+  // blockaddresses.
+  return materializeForwardReferencedFunctions();
 }
 
 bool BitcodeReader::isDematerializable(const GlobalValue *GV) const {
   const Function *F = dyn_cast<Function>(GV);
   if (!F || F->isDeclaration())
     return false;
+
+  // Dematerializing F would leave dangling references that wouldn't be
+  // reconnected on re-materialization.
+  if (BlockAddressesTaken.count(F))
+    return false;
+
   return DeferredFunctionInfo.count(const_cast<Function*>(F));
 }
 
@@ -3299,6 +3330,10 @@ void BitcodeReader::Dematerialize(GlobalValue *GV) {
 std::error_code BitcodeReader::MaterializeModule(Module *M) {
   assert(M == TheModule &&
          "Can only Materialize the Module this BitcodeReader is attached to.");
+
+  // Promise to materialize all forward references.
+  WillMaterializeAllForwardRefs = true;
+
   // Iterate over the module, deserializing any functions that are still on
   // disk.
   for (Module::iterator F = TheModule->begin(), E = TheModule->end();
@@ -3314,6 +3349,11 @@ std::error_code BitcodeReader::MaterializeModule(Module *M) {
   if (NextUnreadBit)
     ParseModule(true);
 
+  // Check that all block address forward references got resolved (as we
+  // promised above).
+  if (!BlockAddrFwdRefs.empty())
+    return Error(BitcodeError::NeverResolvedFunctionFromBlockAddress);
+
   // Upgrade any intrinsic calls that slipped through (should not happen!) and
   // delete the old functions to clean up. We can't do this unless the entire
   // module is materialized because there could always be another function body
@@ -3431,6 +3471,8 @@ class BitcodeErrorCategoryType : public std::error_category {
       return "Invalid multiple blocks";
     case BitcodeError::NeverResolvedValueFoundInFunction:
       return "Never resolved value found in function";
+    case BitcodeError::NeverResolvedFunctionFromBlockAddress:
+      return "Never resolved function from blockaddress";
     case BitcodeError::InvalidValue:
       return "Invalid value";
     }
@@ -3455,13 +3497,18 @@ ErrorOr<Module *> llvm::getLazyBitcodeModule(MemoryBuffer *Buffer,
   Module *M = new Module(Buffer->getBufferIdentifier(), Context);
   BitcodeReader *R = new BitcodeReader(Buffer, Context);
   M->setMaterializer(R);
-  if (std::error_code EC = R->ParseBitcodeInto(M)) {
+
+  auto cleanupOnError = [&](std::error_code EC) {
     R->releaseBuffer(); // Never take ownership on error.
     delete M;  // Also deletes R.
     return EC;
-  }
+  };
 
-  R->materializeForwardReferencedFunctions();
+  if (std::error_code EC = R->ParseBitcodeInto(M))
+    return cleanupOnError(EC);
+
+  if (std::error_code EC = R->materializeForwardReferencedFunctions())
+    return cleanupOnError(EC);
 
   return M;
 }
diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index 40f8d134f6a..341e134302d 100644
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -193,20 +193,29 @@ class BitcodeReader : public GVMaterializer {
   /// not need this flag.
   bool UseRelativeIDs;
 
+  /// True if all functions will be materialized, negating the need to process
+  /// (e.g.) blockaddress forward references.
+  bool WillMaterializeAllForwardRefs;
+
+  /// Functions that have block addresses taken.  This is usually empty.
+  SmallPtrSet<const Function *, 4> BlockAddressesTaken;
+
 public:
   std::error_code Error(BitcodeError E) { return make_error_code(E); }
 
   explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext &C)
       : Context(C), TheModule(nullptr), Buffer(buffer), LazyStreamer(nullptr),
         NextUnreadBit(0), SeenValueSymbolTable(false), ValueList(C),
-        MDValueList(C), SeenFirstFunctionBody(false), UseRelativeIDs(false) {}
+        MDValueList(C), SeenFirstFunctionBody(false), UseRelativeIDs(false),
+        WillMaterializeAllForwardRefs(false) {}
   explicit BitcodeReader(DataStreamer *streamer, LLVMContext &C)
       : Context(C), TheModule(nullptr), Buffer(nullptr), LazyStreamer(streamer),
         NextUnreadBit(0), SeenValueSymbolTable(false), ValueList(C),
-        MDValueList(C), SeenFirstFunctionBody(false), UseRelativeIDs(false) {}
+        MDValueList(C), SeenFirstFunctionBody(false), UseRelativeIDs(false),
+        WillMaterializeAllForwardRefs(false) {}
   ~BitcodeReader() { FreeState(); }
 
-  void materializeForwardReferencedFunctions();
+  std::error_code materializeForwardReferencedFunctions();
 
   void FreeState();
 
diff --git a/unittests/Bitcode/BitReaderTest.cpp b/unittests/Bitcode/BitReaderTest.cpp
index 144853d4d78..8331527437b 100644
--- a/unittests/Bitcode/BitReaderTest.cpp
+++ b/unittests/Bitcode/BitReaderTest.cpp
@@ -70,6 +70,74 @@ TEST(BitReaderTest, MaterializeFunctionsForBlockAddr) { // PR11677
                     "  unreachable\n"
                     "}\n");
   EXPECT_FALSE(verifyModule(*M, &dbgs()));
+
+  // Try (and fail) to dematerialize @func.
+  M->getFunction("func")->Dematerialize();
+  EXPECT_FALSE(M->getFunction("func")->empty());
+}
+
+TEST(BitReaderTest, MaterializeFunctionsForBlockAddrInFunctionBefore) {
+  SmallString<1024> Mem;
+
+  LLVMContext Context;
+  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
+      Context, Mem, "define i8* @before() {\n"
+                    "  ret i8* blockaddress(@func, %bb)\n"
+                    "}\n"
+                    "define void @other() {\n"
+                    "  unreachable\n"
+                    "}\n"
+                    "define void @func() {\n"
+                    "  unreachable\n"
+                    "bb:\n"
+                    "  unreachable\n"
+                    "}\n");
+  EXPECT_TRUE(M->getFunction("before")->empty());
+  EXPECT_TRUE(M->getFunction("func")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
+
+  // Materialize @before, pulling in @func.
+  EXPECT_FALSE(M->getFunction("before")->Materialize());
+  EXPECT_FALSE(M->getFunction("func")->empty());
+  EXPECT_TRUE(M->getFunction("other")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
+
+  // Try (and fail) to dematerialize @func.
+  M->getFunction("func")->Dematerialize();
+  EXPECT_FALSE(M->getFunction("func")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
+}
+
+TEST(BitReaderTest, MaterializeFunctionsForBlockAddrInFunctionAfter) {
+  SmallString<1024> Mem;
+
+  LLVMContext Context;
+  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
+      Context, Mem, "define void @func() {\n"
+                    "  unreachable\n"
+                    "bb:\n"
+                    "  unreachable\n"
+                    "}\n"
+                    "define void @other() {\n"
+                    "  unreachable\n"
+                    "}\n"
+                    "define i8* @after() {\n"
+                    "  ret i8* blockaddress(@func, %bb)\n"
+                    "}\n");
+  EXPECT_TRUE(M->getFunction("after")->empty());
+  EXPECT_TRUE(M->getFunction("func")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
+
+  // Materialize @after, pulling in @func.
+  EXPECT_FALSE(M->getFunction("after")->Materialize());
+  EXPECT_FALSE(M->getFunction("func")->empty());
+  EXPECT_TRUE(M->getFunction("other")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
+
+  // Try (and fail) to dematerialize @func.
+  M->getFunction("func")->Dematerialize();
+  EXPECT_FALSE(M->getFunction("func")->empty());
+  EXPECT_FALSE(verifyModule(*M, &dbgs()));
 }
 
 } // end namespace