Index: llvm/trunk/include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- llvm/trunk/include/llvm/Bitcode/LLVMBitCodes.h
+++ llvm/trunk/include/llvm/Bitcode/LLVMBitCodes.h
@@ -261,6 +261,8 @@
   //                   numrefs x valueid,
   //                   n x (valueid, relblockfreq)]
   FS_PERMODULE_RELBF = 19,
+  // Index-wide flags
+  FS_FLAGS = 20,
 };
 
 enum MetadataCodes {
Index: llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
+++ llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5133,6 +5133,16 @@
     switch (BitCode) {
     default: // Default behavior: ignore.
       break;
+    case bitc::FS_FLAGS: {  // [flags]
+      uint64_t Flags = Record[0];
+      // Scan flags (set only on the combined index).
+      assert(Flags <= 1 && "Unexpected bits in flag");
+
+      // 1 bit: WithGlobalValueDeadStripping flag.
+      if (Flags & 0x1)
+        TheIndex.setWithGlobalValueDeadStripping();
+      break;
+    }
     case bitc::FS_VALUE_GUID: { // [valueid, refguid]
       uint64_t ValueID = Record[0];
       GlobalValue::GUID RefGUID = Record[1];
Index: llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -3552,6 +3552,11 @@
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
 
+  // Write the index flags. Currently we only write a single flag, the value of
+  // withGlobalValueDeadStripping, which only applies to the combined index.
+  Stream.EmitRecord(bitc::FS_FLAGS,
+                    ArrayRef<uint64_t>{Index.withGlobalValueDeadStripping()});
+
   for (const auto &GVI : valueIds()) {
     Stream.EmitRecord(bitc::FS_VALUE_GUID,
                       ArrayRef<uint64_t>{GVI.second, GVI.first});
Index: llvm/trunk/test/Bitcode/thinlto-alias.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-alias.ll
+++ llvm/trunk/test/Bitcode/thinlto-alias.ll
@@ -22,6 +22,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; See if the call to analias is registered, using the expected value id.
 ; COMBINED-NEXT:    <VALUE_GUID op0=[[ALIASID:[0-9]+]] op1=-5751648690987223394/>
 ; COMBINED-NEXT:    <VALUE_GUID
Index: llvm/trunk/test/Bitcode/thinlto-deadstrip-flag.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-deadstrip-flag.ll
+++ llvm/trunk/test/Bitcode/thinlto-deadstrip-flag.ll
@@ -0,0 +1,20 @@
+; REQUIRES: x86-registered-target
+; RUN: opt -module-summary %s -o %t.o
+
+; Ensure dead stripping performed flag is set on distributed index
+; RUN: llvm-lto2 run %t.o -o %t.out -thinlto-distributed-indexes \
+; RUN:		-r %t.o,glob,plx
+; RUN: llvm-bcanalyzer -dump %t.o.thinlto.bc | FileCheck %s --check-prefix=WITHDEAD
+; WITHDEAD: <FLAGS op0=1/>
+
+; Ensure dead stripping performed flag is not set on distributed index
+; when option used to disable dead stripping computation.
+; RUN: llvm-lto2 run %t.o -o %t.out -thinlto-distributed-indexes \
+; RUN:		-r %t.o,glob,plx -compute-dead=false
+; RUN: llvm-bcanalyzer -dump %t.o.thinlto.bc | FileCheck %s --check-prefix=NODEAD
+; NODEAD: <FLAGS op0=0/>
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@glob = global i32 0
Index: llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
+++ llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
@@ -24,6 +24,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; COMBINED-NEXT:    <VALUE_GUID op0=[[FUNCID:[0-9]+]] op1=7289175272376759421/>
 ; COMBINED-NEXT:    <VALUE_GUID
 ; COMBINED-NEXT:    <COMBINED
Index: llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
+++ llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
@@ -37,6 +37,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; COMBINED-NEXT:    <VALUE_GUID
 ; COMBINED-NEXT:    <VALUE_GUID
 ; COMBINED-NEXT:    <VALUE_GUID
Index: llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
+++ llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
@@ -39,6 +39,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; COMBINED-NEXT:    <VALUE_GUID
 ; COMBINED-NEXT:    <VALUE_GUID
 ; COMBINED-NEXT:    <VALUE_GUID
Index: llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph.ll
+++ llvm/trunk/test/Bitcode/thinlto-function-summary-callgraph.ll
@@ -26,6 +26,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; Only 2 VALUE_GUID since reference to undefinedglob should not be included in
 ; combined index.
 ; COMBINED-NEXT:    <VALUE_GUID op0=[[FUNCID:[0-9]+]] op1=7289175272376759421/>
Index: llvm/trunk/test/Bitcode/thinlto-function-summary-originalnames.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-function-summary-originalnames.ll
+++ llvm/trunk/test/Bitcode/thinlto-function-summary-originalnames.ll
@@ -5,6 +5,7 @@
 
 ; COMBINED:       <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT:    <VERSION
+; COMBINED-NEXT:    <FLAGS
 ; COMBINED-NEXT:    <VALUE_GUID {{.*}} op1=4947176790635855146/>
 ; COMBINED-NEXT:    <VALUE_GUID {{.*}} op1=-6591587165810580810/>
 ; COMBINED-NEXT:    <VALUE_GUID {{.*}} op1=-4377693495213223786/>
Index: llvm/trunk/test/tools/gold/X86/thinlto.ll
===================================================================
--- llvm/trunk/test/tools/gold/X86/thinlto.ll
+++ llvm/trunk/test/tools/gold/X86/thinlto.ll
@@ -95,6 +95,7 @@
 ; BACKEND1-NEXT: </MODULE_STRTAB_BLOCK
 ; BACKEND1-NEXT: <GLOBALVAL_SUMMARY_BLOCK
 ; BACKEND1-NEXT: <VERSION
+; BACKEND1-NEXT: <FLAGS
 ; BACKEND1-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; BACKEND1-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; BACKEND1-NEXT: <COMBINED
@@ -108,6 +109,7 @@
 ; BACKEND2-NEXT: </MODULE_STRTAB_BLOCK
 ; BACKEND2-NEXT: <GLOBALVAL_SUMMARY_BLOCK
 ; BACKEND2-NEXT: <VERSION
+; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
@@ -118,6 +120,7 @@
 ; COMBINED-NEXT: </MODULE_STRTAB_BLOCK
 ; COMBINED-NEXT: <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT: <VERSION
+; COMBINED-NEXT: <FLAGS
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <COMBINED
Index: llvm/trunk/test/tools/llvm-lto/thinlto.ll
===================================================================
--- llvm/trunk/test/tools/llvm-lto/thinlto.ll
+++ llvm/trunk/test/tools/llvm-lto/thinlto.ll
@@ -11,6 +11,7 @@
 ; COMBINED-NEXT: </MODULE_STRTAB_BLOCK
 ; COMBINED-NEXT: <GLOBALVAL_SUMMARY_BLOCK
 ; COMBINED-NEXT: <VERSION
+; COMBINED-NEXT: <FLAGS
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <COMBINED
Index: llvm/trunk/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
===================================================================
--- llvm/trunk/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
+++ llvm/trunk/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
@@ -315,6 +315,7 @@
       STRINGIFY_CODE(FS, COMBINED_ALIAS)
       STRINGIFY_CODE(FS, COMBINED_ORIGINAL_NAME)
       STRINGIFY_CODE(FS, VERSION)
+      STRINGIFY_CODE(FS, FLAGS)
       STRINGIFY_CODE(FS, TYPE_TESTS)
       STRINGIFY_CODE(FS, TYPE_TEST_ASSUME_VCALLS)
       STRINGIFY_CODE(FS, TYPE_CHECKED_LOAD_VCALLS)