diff --git a/lld/test/COFF/thinlto-index-only.ll b/lld/test/COFF/thinlto-index-only.ll
--- a/lld/test/COFF/thinlto-index-only.ll
+++ b/lld/test/COFF/thinlto-index-only.ll
@@ -39,7 +39,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT op0=2/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ; Thin archive tests. Check that the module paths point to the original files.
diff --git a/lld/test/ELF/lto/thinlto-emit-index.ll b/lld/test/ELF/lto/thinlto-emit-index.ll
--- a/lld/test/ELF/lto/thinlto-emit-index.ll
+++ b/lld/test/ELF/lto/thinlto-emit-index.ll
@@ -92,7 +92,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT op0=2/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/lld/test/ELF/lto/thinlto-index-only.ll b/lld/test/ELF/lto/thinlto-index-only.ll
--- a/lld/test/ELF/lto/thinlto-index-only.ll
+++ b/lld/test/ELF/lto/thinlto-index-only.ll
@@ -90,7 +90,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT op0=2/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/lld/test/MachO/thinlto-emit-index.ll b/lld/test/MachO/thinlto-emit-index.ll
--- a/lld/test/MachO/thinlto-emit-index.ll
+++ b/lld/test/MachO/thinlto-emit-index.ll
@@ -92,7 +92,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT op0=2/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 
diff --git a/lld/test/MachO/thinlto-index-only.ll b/lld/test/MachO/thinlto-index-only.ll
--- a/lld/test/MachO/thinlto-index-only.ll
+++ b/lld/test/MachO/thinlto-index-only.ll
@@ -91,7 +91,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT op0=2/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ;--- f.ll
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
--- a/llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ b/llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -1333,6 +1333,11 @@
 
   // The total number of basic blocks in the module in the per-module summary or
   // the total number of basic blocks in the LTO unit in the combined index.
+  // FIXME: Putting this in the distributed ThinLTO index files breaks LTO
+  // backend caching on any BB change to any linked file. It is currently not
+  // used except in the case of a SamplePGO partial profile, and should be
+  // reevaluated/redesigned to allow more effective incremental builds in that
+  // case.
   uint64_t BlockCount;
 
   // List of unique stack ids (hashes). We use a 4B index of the id in the
diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
--- a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
+++ b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -80,6 +80,8 @@
     "module-summary-dot-file", cl::Hidden, cl::value_desc("filename"),
     cl::desc("File to emit dot graph of new summary into"));
 
+extern cl::opt<bool> ScalePartialSampleProfileWorkingSetSize;
+
 // Walk through the operands of a given User via worklist iteration and populate
 // the set of GlobalValue references encountered. Invoked either on an
 // Instruction or a GlobalVariable (which walks its initializer).
@@ -477,7 +479,9 @@
       }
     }
   }
-  Index.addBlockCount(F.size());
+
+  if (PSI->hasPartialSampleProfile() && ScalePartialSampleProfileWorkingSetSize)
+    Index.addBlockCount(F.size());
 
   std::vector<ValueInfo> Refs;
   if (IsThinLTO) {
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -4247,8 +4247,9 @@
     NameVals.clear();
   }
 
-  Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
-                    ArrayRef<uint64_t>{Index->getBlockCount()});
+  if (Index->getBlockCount())
+    Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
+                      ArrayRef<uint64_t>{Index->getBlockCount()});
 
   Stream.ExitBlock();
 }
@@ -4578,8 +4579,9 @@
     }
   }
 
-  Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
-                    ArrayRef<uint64_t>{Index.getBlockCount()});
+  if (Index.getBlockCount())
+    Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
+                      ArrayRef<uint64_t>{Index.getBlockCount()});
 
   Stream.ExitBlock();
 }
diff --git a/llvm/test/Bitcode/Inputs/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll b/llvm/test/Bitcode/Inputs/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Bitcode/Inputs/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll
@@ -0,0 +1,50 @@
+; ModuleID = 'thinlto-function-summary-callgraph-profile-summary2.ll'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @hot1() #1 {
+  ret void
+}
+define void @hot2() #1 {
+  ret void
+}
+define void @hot3() #1 {
+  ret void
+}
+define void @cold1() #1 {
+  ret void
+}
+define void @cold2() #1 {
+  ret void
+}
+define void @cold3() #1 {
+  ret void
+}
+define void @none1() #1 {
+  ret void
+}
+define void @none2() #1 {
+  ret void
+}
+define void @none3() #1 {
+  ret void
+}
+
+!llvm.module.flags = !{!1}
+
+!1 = !{i32 1, !"ProfileSummary", !2}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10, !11, !12}
+!3 = !{!"ProfileFormat", !"SampleProfile"}
+!4 = !{!"TotalCount", i64 10000}
+!5 = !{!"MaxCount", i64 10}
+!6 = !{!"MaxInternalCount", i64 1}
+!7 = !{!"MaxFunctionCount", i64 1000}
+!8 = !{!"NumCounts", i64 3}
+!9 = !{!"NumFunctions", i64 3}
+!10 = !{!"IsPartialProfile", i64 1}
+!11 = !{!"PartialProfileRatio", double 0.5}
+!12 = !{!"DetailedSummary", !13}
+!13 = !{!14, !15, !16}
+!14 = !{i32 10000, i64 100, i32 1}
+!15 = !{i32 999000, i64 100, i32 1}
+!16 = !{i32 999999, i64 1, i32 2}
diff --git a/llvm/test/Bitcode/thinlto-alias.ll b/llvm/test/Bitcode/thinlto-alias.ll
--- a/llvm/test/Bitcode/thinlto-alias.ll
+++ b/llvm/test/Bitcode/thinlto-alias.ll
@@ -22,7 +22,6 @@
 ; See if the call to func is registered.
 ; The value id 1 matches the second FUNCTION record above.
 ; CHECK-NEXT:    <PERMODULE {{.*}} op7=1/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=1/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; CHECK: <STRTAB_BLOCK
@@ -38,7 +37,6 @@
 ; COMBINED-NEXT:    <COMBINED {{.*}} op9=[[ALIASID]]/>
 ; COMBINED-NEXT:    <COMBINED {{.*}}
 ; COMBINED-NEXT:    <COMBINED_ALIAS  {{.*}} op3=[[ALIASEEID]]
-; COMBINED-NEXT:    <BLOCK_COUNT op0=2/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK
 
 ; ModuleID = 'thinlto-function-summary-callgraph.ll'
@@ -57,11 +55,9 @@
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
 ; DIS: ^1 = gv: (name: "analias", summaries: (alias: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), aliasee: ^2))) ; guid = 12695095382722328222
 ; DIS: ^2 = gv: (name: "aliasee", summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1))) ; guid = 17407585008595848568
-; DIS: ^3 = blockcount: 1
 
 ; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-alias.ll.tmp.o", hash: (0, 0, 0, 0, 0))
 ; COMBINED-DIS: ^1 = module: (path: "{{.*}}thinlto-alias.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
 ; COMBINED-DIS: ^2 = gv: (guid: 12695095382722328222, summaries: (alias: (module: ^1, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), aliasee: ^4)))
 ; COMBINED-DIS: ^3 = gv: (guid: 15822663052811949562, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^2)))))
 ; COMBINED-DIS: ^4 = gv: (guid: 17407585008595848568, summaries: (function: (module: ^1, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
-; COMBINED-DIS: ^5 = blockcount: 2
diff --git a/llvm/test/Bitcode/thinlto-alias2.ll b/llvm/test/Bitcode/thinlto-alias2.ll
--- a/llvm/test/Bitcode/thinlto-alias2.ll
+++ b/llvm/test/Bitcode/thinlto-alias2.ll
@@ -8,7 +8,6 @@
 ; CHECK-NEXT:    <PERMODULE {{.*}} op4=0 op5=0 op6=0 op7=[[ALIASID:[0-9]+]]/>
 ; CHECK-NEXT:    <PERMODULE {{.*}} op0=[[ALIASEEID:[0-9]+]]
 ; CHECK-NEXT:    <ALIAS {{.*}} op0=[[ALIASID]] {{.*}} op2=[[ALIASEEID]]/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=2/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; ModuleID = 'thinlto-alias2.ll'
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
@@ -12,7 +12,6 @@
 ; CHECK-NEXT:    <PERMODULE {{.*}}/>
 ; CHECK-NEXT:    <PERMODULE {{.*}} op0=[[ALIASEEID:[0-9]+]]
 ; CHECK-NEXT:    <ALIAS {{.*}} op0=[[ALIASID]] {{.*}} op2=[[ALIASEEID]]/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=3/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; ModuleID = 'thinlto-function-summary-callgraph-cast.ll'
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll
copy from llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
copy to llvm/test/Bitcode/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll
@@ -1,7 +1,7 @@
 ; Test to check the callgraph in summary when there is PGO
 ; RUN: opt -module-summary %s -o %t.o
 ; RUN: llvm-bcanalyzer -dump %t.o | FileCheck %s
-; RUN: opt -module-summary %p/Inputs/thinlto-function-summary-callgraph-sample-profile-summary.ll -o %t2.o
+; RUN: opt -module-summary %p/Inputs/thinlto-function-summary-callgraph-partial-sample-profile-summary.ll -o %t2.o
 ; RUN: llvm-lto -thinlto -o %t3 %t.o %t2.o
 ; RUN: llvm-bcanalyzer -dump %t3.thinlto.bc | FileCheck %s --check-prefix=COMBINED
 
@@ -30,9 +30,9 @@
 ; CHECK-LABEL:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
 ; CHECK-NEXT:    <FLAGS
-; CHECK-NEXT:    <VALUE_GUID op0=26 op1=123/>
+; CHECK-NEXT:    <VALUE_GUID op0=27 op1=123/>
 ; op4=none1 op6=hot1 op8=cold1 op10=none2 op12=hot2 op14=cold2 op16=none3 op18=hot3 op20=cold3 op22=123
-; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op7=7 op8=0 op9=1 op10=3 op11=4 op12=1 op13=8 op14=0 op15=2 op16=3 op17=5 op18=1 op19=9 op20=0 op21=3 op22=3 op23=6 op24=1 op25=26 op26=4/>
+; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op7=7 op8=0 op9=1 op10=3 op11=4 op12=1 op13=8 op14=0 op15=2 op16=3 op17=5 op18=1 op19=9 op20=0 op21=3 op22=3 op23=6 op24=1 op25=27 op26=4/>
 ; CHECK-NEXT:    <BLOCK_COUNT op0=4/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
@@ -74,18 +74,18 @@
 define void @hot_function(i1 %a, i1 %a2) !prof !20 {
 entry:
   call void @none1()
-  call void @hot1(), !prof !15
-  call void @cold1(), !prof !16
+  call void @hot1(), !prof !17
+  call void @cold1(), !prof !18
   br i1 %a, label %Cold, label %Hot, !prof !41
 Cold:           ; 1/1000 goes here
   call void @none2()
-  call void @hot2(), !prof !15
-  call void @cold2(), !prof !16
+  call void @hot2(), !prof !17
+  call void @cold2(), !prof !18
   br label %exit
 Hot:            ; 999/1000 goes here
   call void @none3()
-  call void @hot3(), !prof !15
-  call void @cold3(), !prof !16
+  call void @hot3(), !prof !17
+  call void @cold3(), !prof !18
   br label %exit
 exit:
   ret void
@@ -107,7 +107,7 @@
 !20 = !{!"function_entry_count", i64 110, i64 123}
 
 !1 = !{i32 1, !"ProfileSummary", !2}
-!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10, !11, !12}
 !3 = !{!"ProfileFormat", !"SampleProfile"}
 !4 = !{!"TotalCount", i64 10000}
 !5 = !{!"MaxCount", i64 10}
@@ -115,10 +115,12 @@
 !7 = !{!"MaxFunctionCount", i64 1000}
 !8 = !{!"NumCounts", i64 3}
 !9 = !{!"NumFunctions", i64 3}
-!10 = !{!"DetailedSummary", !11}
-!11 = !{!12, !13, !14}
-!12 = !{i32 10000, i64 100, i32 1}
-!13 = !{i32 999000, i64 100, i32 1}
-!14 = !{i32 999999, i64 1, i32 2}
-!15 = !{!"branch_weights", i32 100}
-!16 = !{!"branch_weights", i32 1}
+!10 = !{!"IsPartialProfile", i64 1}
+!11 = !{!"PartialProfileRatio", double 0.5}
+!12 = !{!"DetailedSummary", !13}
+!13 = !{!14, !15, !16}
+!14 = !{i32 10000, i64 100, i32 1}
+!15 = !{i32 999000, i64 100, i32 1}
+!16 = !{i32 999999, i64 1, i32 2}
+!17 = !{!"branch_weights", i32 100}
+!18 = !{!"branch_weights", i32 1}
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
@@ -19,7 +19,6 @@
 ; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered, using the expected hotness type.
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op7=1 op8=2/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=1/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 ; CHECK: <STRTAB_BLOCK
 ; CHECK-NEXT: blob data = 'mainfunc{{.*}}'
@@ -33,7 +32,6 @@
 ; See if the call to func is registered, using the expected hotness type.
 ; op6=2 which is hotnessType::None.
 ; COMBINED-NEXT:    <COMBINED_PROFILE {{.*}} op9=[[FUNCID]] op10=2/>
-; COMBINED-NEXT:    <BLOCK_COUNT op0=2/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; ModuleID = 'thinlto-function-summary-callgraph.ll'
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
@@ -50,7 +50,6 @@
 ; CHECK-NEXT:    <VALUE_GUID op0=25 op1=123/>
 ; op4=hot1 op6=cold op8=hot2 op10=hot4 op12=none1 op14=hot3 op16=none2 op18=none3 op20=123
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op7=1 op8=3 op9=5 op10=1 op11=2 op12=3 op13=4 op14=1 op15=6 op16=2 op17=3 op18=3 op19=7 op20=2 op21=8 op22=2 op23=25 op24=4/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=6/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; CHECK: <STRTAB_BLOCK
@@ -75,7 +74,6 @@
 ; COMBINED-NEXT:    <COMBINED abbrevid=
 ; COMBINED-NEXT:    <COMBINED_PROFILE {{.*}} op9=[[HOT1:.*]] op10=3 op11=[[COLD:.*]] op12=1 op13=[[HOT2:.*]] op14=3 op15=[[NONE1:.*]] op16=2 op17=[[HOT3:.*]] op18=3 op19=[[NONE2:.*]] op20=2 op21=[[NONE3:.*]] op22=2/>
 ; COMBINED-NEXT:    <COMBINED abbrevid=
-; COMBINED-NEXT:    <BLOCK_COUNT op0=13/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
@@ -15,7 +15,6 @@
 ; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered.
 ; CHECK-NEXT:    <PERMODULE_RELBF {{.*}} op4=1 {{.*}} op9=256
-; CHECK-NEXT:    <BLOCK_COUNT op0=1/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 ; CHECK: <STRTAB_BLOCK
 ; CHECK-NEXT: blob data = 'undefinedglobmainfunc{{.*}}'
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
@@ -33,7 +33,6 @@
 ; CHECK-NEXT:    <VALUE_GUID op0=26 op1=123/>
 ; op4=none1 op6=hot1 op8=cold1 op10=none2 op12=hot2 op14=cold2 op16=none3 op18=hot3 op20=cold3 op22=123
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op7=7 op8=0 op9=1 op10=3 op11=4 op12=1 op13=8 op14=0 op15=2 op16=3 op17=5 op18=1 op19=9 op20=0 op21=3 op22=3 op23=6 op24=1 op25=26 op26=4/>
-; CHECK-NEXT:    <BLOCK_COUNT op0=4/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; CHECK: <STRTAB_BLOCK
@@ -62,7 +61,6 @@
 ; COMBINED-NEXT:    <COMBINED abbrevid=
 ; COMBINED-NEXT:    <COMBINED_PROFILE {{.*}} op9=[[NONE1:.*]] op10=0 op11=[[HOT1:.*]] op12=3 op13=[[COLD1:.*]] op14=1 op15=[[NONE2:.*]] op16=0 op17=[[HOT2:.*]] op18=3 op19=[[COLD2:.*]] op20=1 op21=[[NONE3:.*]] op22=0 op23=[[HOT3:.*]] op24=3 op25=[[COLD3:.*]] op26=1/>
 ; COMBINED-NEXT:    <COMBINED abbrevid=
-; COMBINED-NEXT:    <BLOCK_COUNT op0=13/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
@@ -20,7 +20,6 @@
 ; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered
 ; CHECK-NEXT:    <PERMODULE {{.*}} op4=1
-; CHECK-NEXT:    <BLOCK_COUNT op0=1/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 ; CHECK: <STRTAB_BLOCK
 ; CHECK-NEXT: blob data = 'undefinedglobmainfunc{{.*}}'
@@ -36,7 +35,6 @@
 ; COMBINED-NEXT:    <COMBINED
 ; See if the call to func is registered.
 ; COMBINED-NEXT:    <COMBINED {{.*}} op9=[[FUNCID]]/>
-; COMBINED-NEXT:    <BLOCK_COUNT op0=2/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; ModuleID = 'thinlto-function-summary-callgraph.ll'
diff --git a/llvm/test/Bitcode/thinlto-function-summary-originalnames.ll b/llvm/test/Bitcode/thinlto-function-summary-originalnames.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-originalnames.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-originalnames.ll
@@ -15,7 +15,6 @@
 ; COMBINED-DAG:    <COMBINED_ORIGINAL_NAME op0=-2012135647395072713/>
 ; COMBINED-DAG:    <COMBINED_ALIAS
 ; COMBINED-DAG:    <COMBINED_ORIGINAL_NAME op0=-4170563161550796836/>
-; COMBINED-NEXT:   <BLOCK_COUNT op0=1/>
 ; COMBINED-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 source_filename = "/path/to/source.c"
diff --git a/llvm/test/Bitcode/thinlto-function-summary-paramaccess.ll b/llvm/test/Bitcode/thinlto-function-summary-paramaccess.ll
--- a/llvm/test/Bitcode/thinlto-function-summary-paramaccess.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-paramaccess.ll
@@ -338,4 +338,3 @@
 ; COMBINED-NEXT: <COMBINED abbrevid=4 op0=18
 ; COMBINED-NEXT: <PARAM_ACCESS op0=0 op1=0 op2=0 op3=1 op4=0 op5=[[CALLEE2]] op6=1431 op7=250/>
 ; COMBINED-NEXT: <COMBINED abbrevid=4 op0=19
-; COMBINED-NEXT: <BLOCK_COUNT op0=19/>
\ No newline at end of file
diff --git a/llvm/test/Bitcode/thinlto-function-summary.ll b/llvm/test/Bitcode/thinlto-function-summary.ll
--- a/llvm/test/Bitcode/thinlto-function-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary.ll
@@ -24,7 +24,6 @@
 ; BC-NEXT: <PERMODULE {{.*}} op0=3 op1=7
 ; BC-NEXT: <PERMODULE {{.*}} op0=4 op1=0 op2=4 op3=0
 ; BC-NEXT: <ALIAS {{.*}} op0=6 op1=0 op2=3
-; BC-NEXT: <BLOCK_COUNT op0=5/>
 ; BC-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 ; BC: <STRTAB_BLOCK
 ; BC-NEXT: blob data = 'hfoobaranon.{{................................}}.0variadicllvm.va_startf{{.*}}'
diff --git a/llvm/test/Bitcode/thinlto-index-disassembled-by-llvm-dis.ll b/llvm/test/Bitcode/thinlto-index-disassembled-by-llvm-dis.ll
--- a/llvm/test/Bitcode/thinlto-index-disassembled-by-llvm-dis.ll
+++ b/llvm/test/Bitcode/thinlto-index-disassembled-by-llvm-dis.ll
@@ -19,7 +19,6 @@
 
 ; DIS: ^0 = module: (path: "{{.*}}thinlto-index-disassembled-by-llvm-dis.ll.tmp
 ; DIS: ^1 = gv: (name: "aplusb", summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2))) ; guid = 
-; DIS: ^2 = blockcount: 1
 
 source_filename = "add.cpp"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/ThinLTO/X86/distributed_indexes.ll b/llvm/test/ThinLTO/X86/distributed_indexes.ll
--- a/llvm/test/ThinLTO/X86/distributed_indexes.ll
+++ b/llvm/test/ThinLTO/X86/distributed_indexes.ll
@@ -25,7 +25,6 @@
 ; BACKEND1-NEXT: <COMBINED {{.*}} op1=0
 ; BACKEND1-NEXT: <COMBINED {{.*}} op1=1
 ; BACKEND1-NEXT: <COMBINED_ALIAS {{.*}} op1=1
-; BACKEND1-NEXT: <BLOCK_COUNT op0=4/>
 ; BACKEND1-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ; The backend index for Input/distributed_indexes.ll contains summaries from
@@ -41,7 +40,6 @@
 ; BACKEND2-NEXT: <COMBINED
 ; BACKEND2-NEXT: <COMBINED
 ; BACKEND2-NEXT: <COMBINED_ALIAS
-; BACKEND2-NEXT: <BLOCK_COUNT op0=4/>
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ; Make sure that when the alias is imported as a copy of the aliasee, but the
diff --git a/llvm/test/tools/gold/X86/thinlto.ll b/llvm/test/tools/gold/X86/thinlto.ll
--- a/llvm/test/tools/gold/X86/thinlto.ll
+++ b/llvm/test/tools/gold/X86/thinlto.ll
@@ -107,7 +107,6 @@
 ; BACKEND1-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; BACKEND1-NEXT: <COMBINED
 ; BACKEND1-NEXT: <COMBINED
-; BACKEND1-NEXT: <BLOCK_COUNT
 ; BACKEND1-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ; The backend index for Input/thinlto.ll contains summaries from itself only,
@@ -120,7 +119,6 @@
 ; BACKEND2-NEXT: <FLAGS
 ; BACKEND2-NEXT: <VALUE_GUID op0=1 op1=-5300342847281564238
 ; BACKEND2-NEXT: <COMBINED
-; BACKEND2-NEXT: <BLOCK_COUNT
 ; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 ; DIS1: ^0 = module: (path: "{{.*}}thinlto.ll.tmp.o", hash: (0, 0, 0, 0, 0))
@@ -142,7 +140,6 @@
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <COMBINED
 ; COMBINED-NEXT: <COMBINED
-; COMBINED-NEXT: <BLOCK_COUNT
 ; COMBINED-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/tools/llvm-lto/thinlto.ll b/llvm/test/tools/llvm-lto/thinlto.ll
--- a/llvm/test/tools/llvm-lto/thinlto.ll
+++ b/llvm/test/tools/llvm-lto/thinlto.ll
@@ -16,7 +16,6 @@
 ; COMBINED-NEXT: <VALUE_GUID op0={{1|2}} op1={{-3706093650706652785|-5300342847281564238}}
 ; COMBINED-NEXT: <COMBINED
 ; COMBINED-NEXT: <COMBINED
-; COMBINED-NEXT: <BLOCK_COUNT op0=2/>
 ; COMBINED-NEXT: </GLOBALVAL_SUMMARY_BLOCK
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"