Index: llvm/include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -261,6 +261,11 @@
   //                   numrefs x valueid,
   //                   n x (valueid, relblockfreq)]
   FS_PERMODULE_RELBF = 19,
+  // Maps type identifier to summary information for that type identifier.
+  // TYPE_ID: [typeid, kind, bitwidth, align, size, bitmask, inlinebits,
+  //           n x (typeid, kind, name, numrba,
+  //                numrba x (numarg, numarg x arg, kind, info, byte, bit))]
+  FS_TYPE_ID = 20,
 };
 
 enum MetadataCodes {
Index: llvm/include/llvm/IR/ModuleSummaryIndex.h
===================================================================
--- llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -669,7 +669,6 @@
 
   /// Mapping from type identifiers to summary information for that type
   /// identifier.
-  // FIXME: Add bitcode read/write support for this field.
   std::map<std::string, TypeIdSummary> TypeIdMap;
 
   /// Mapping from original ID to GUID. If original ID can map to multiple
Index: llvm/lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5071,6 +5071,56 @@
   return Ret;
 }
 
+static void
+parseWholeProgramDevirtResolutionByArg(ArrayRef<uint64_t> Record, size_t &Slot,
+                                       WholeProgramDevirtResolution &Wpd) {
+  uint64_t ArgNum = Record[Slot++];
+  WholeProgramDevirtResolution::ByArg &B =
+      Wpd.ResByArg[{Record.begin() + Slot, Record.begin() + Slot + ArgNum}];
+  Slot += ArgNum;
+
+  B.TheKind =
+      static_cast<WholeProgramDevirtResolution::ByArg::Kind>(Record[Slot++]);
+  B.Info = Record[Slot++];
+  B.Byte = Record[Slot++];
+  B.Bit = Record[Slot++];
+}
+
+static void parseWholeProgramDevirtResolution(ArrayRef<uint64_t> Record,
+                                              StringRef Strtab, size_t &Slot,
+                                              TypeIdSummary &TypeId) {
+  uint64_t Id = Record[Slot++];
+  WholeProgramDevirtResolution &Wpd = TypeId.WPDRes[Id];
+
+  Wpd.TheKind = static_cast<WholeProgramDevirtResolution::Kind>(Record[Slot++]);
+  Wpd.SingleImplName = {Strtab.data() + Record[Slot],
+                        static_cast<size_t>(Record[Slot + 1])};
+  Slot += 2;
+
+  uint64_t ResByArgNum = Record[Slot++];
+  for (uint64_t I = 0; I != ResByArgNum; ++I)
+    parseWholeProgramDevirtResolutionByArg(Record, Slot, Wpd);
+}
+
+static void parseTypeIdSummaryRecord(ArrayRef<uint64_t> Record,
+                                     StringRef Strtab,
+                                     ModuleSummaryIndex &TheIndex) {
+  size_t Slot = 0;
+  TypeIdSummary &TypeId = TheIndex.getOrInsertTypeIdSummary(
+      {Strtab.data() + Record[Slot], static_cast<size_t>(Record[Slot + 1])});
+  Slot += 2;
+
+  TypeId.TTRes.TheKind = static_cast<TypeTestResolution::Kind>(Record[Slot++]);
+  TypeId.TTRes.SizeM1BitWidth = Record[Slot++];
+  TypeId.TTRes.AlignLog2 = Record[Slot++];
+  TypeId.TTRes.SizeM1 = Record[Slot++];
+  TypeId.TTRes.BitMask = Record[Slot++];
+  TypeId.TTRes.InlineBits = Record[Slot++];
+
+  while (Slot < Record.size())
+    parseWholeProgramDevirtResolution(Record, Strtab, Slot, TypeId);
+}
+
 // Eagerly parse the entire summary block. This populates the GlobalValueSummary
 // objects in the index.
 Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
@@ -5378,6 +5428,7 @@
             {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});
       break;
     }
+
     case bitc::FS_CFI_FUNCTION_DECLS: {
       std::set<std::string> &CfiFunctionDecls = TheIndex.cfiFunctionDecls();
       for (unsigned I = 0; I != Record.size(); I += 2)
@@ -5385,6 +5436,10 @@
             {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});
       break;
     }
+
+    case bitc::FS_TYPE_ID:
+      parseTypeIdSummaryRecord(Record, Strtab, TheIndex);
+      break;
     }
   }
   llvm_unreachable("Exit infinite loop");
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -3358,6 +3358,51 @@
                      FS->type_checked_load_const_vcalls());
 }
 
+static void writeWholeProgramDevirtResolutionByArg(
+    SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
+    const WholeProgramDevirtResolution::ByArg &ByArg) {
+  NameVals.push_back(args.size());
+  NameVals.insert(NameVals.end(), args.begin(), args.end());
+
+  NameVals.push_back(ByArg.TheKind);
+  NameVals.push_back(ByArg.Info);
+  NameVals.push_back(ByArg.Byte);
+  NameVals.push_back(ByArg.Bit);
+}
+
+static void writeWholeProgramDevirtResolution(
+    SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
+    uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
+  NameVals.push_back(Id);
+
+  NameVals.push_back(Wpd.TheKind);
+  NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
+  NameVals.push_back(Wpd.SingleImplName.size());
+
+  NameVals.push_back(Wpd.ResByArg.size());
+  for (auto &A : Wpd.ResByArg)
+    writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
+}
+
+static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
+                                     StringTableBuilder &StrtabBuilder,
+                                     const std::string &Id,
+                                     const TypeIdSummary &Summary) {
+  NameVals.push_back(StrtabBuilder.add(Id));
+  NameVals.push_back(Id.size());
+
+  NameVals.push_back(Summary.TTRes.TheKind);
+  NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
+  NameVals.push_back(Summary.TTRes.AlignLog2);
+  NameVals.push_back(Summary.TTRes.SizeM1);
+  NameVals.push_back(Summary.TTRes.BitMask);
+  NameVals.push_back(Summary.TTRes.InlineBits);
+
+  for (auto &W : Summary.WPDRes)
+    writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
+                                      W.second);
+}
+
 // Helper to emit a single function summary record.
 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
@@ -3770,6 +3815,14 @@
     NameVals.clear();
   }
 
+  if (!Index.typeIds().empty()) {
+    for (auto &S : Index.typeIds()) {
+      writeTypeIdSummaryRecord(NameVals, StrtabBuilder, S.first, S.second);
+      Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
+      NameVals.clear();
+    }
+  }
+
   Stream.ExitBlock();
 }
 
Index: llvm/test/ThinLTO/X86/cfi-icall.ll
===================================================================
--- llvm/test/ThinLTO/X86/cfi-icall.ll
+++ llvm/test/ThinLTO/X86/cfi-icall.ll
@@ -22,8 +22,9 @@
 ; COMBINED:   <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED:     <CFI_FUNCTION_DEFS op0=0 op1=3/>
 ; COMBINED:     <CFI_FUNCTION_DECLS op0=3 op1=3/>
+; COMBINED:     <TYPE_ID op0=6 op1=7 op2=4 op3=7 op4=0 op5=0 op6=0 op7=0/>
 ; COMBINED:   </GLOBALVAL_SUMMARY_BLOCK>
 
 ; COMBINED:      <STRTAB_BLOCK
-; COMBINED-NEXT:   <BLOB abbrevid=4/> blob data = 'foobar'
+; COMBINED-NEXT:   <BLOB abbrevid=4/> blob data = 'foobartypeid1'
 ; COMBINED-NEXT: </STRTAB_BLOCK>
Index: llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
===================================================================
--- llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
+++ llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
@@ -323,6 +323,7 @@
       STRINGIFY_CODE(FS, VALUE_GUID)
       STRINGIFY_CODE(FS, CFI_FUNCTION_DEFS)
       STRINGIFY_CODE(FS, CFI_FUNCTION_DECLS)
+      STRINGIFY_CODE(FS, TYPE_ID)
     }
   case bitc::METADATA_ATTACHMENT_ID:
     switch(CodeID) {