diff --git a/llvm/include/llvm/AsmParser/LLParser.h b/llvm/include/llvm/AsmParser/LLParser.h
index 9e551d3ae2bbe..2bbcda7093854 100644
--- a/llvm/include/llvm/AsmParser/LLParser.h
+++ b/llvm/include/llvm/AsmParser/LLParser.h
@@ -419,7 +419,7 @@ namespace llvm {
     bool parseParamAccessCall(FunctionSummary::ParamAccess::Call &Call,
                               IdLocListType &IdLocList);
     bool parseParamAccessOffset(ConstantRange &Range);
-    bool parseOptionalRefs(std::vector<ValueInfo> &Refs);
+    bool parseOptionalRefs(SmallVectorImpl<ValueInfo> &Refs);
     bool parseTypeIdEntry(unsigned ID);
     bool parseTypeIdSummary(TypeIdSummary &TIS);
     bool parseTypeIdCompatibleVtableEntry(unsigned ID);
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
index 6d39150a03bfd..7bd90d3ed7e9d 100644
--- a/llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ b/llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -538,10 +538,13 @@ class GlobalValueSummary {
   /// (either by the initializer of a global variable, or referenced
   /// from within a function). This does not include functions called, which
   /// are listed in the derived FunctionSummary object.
-  std::vector<ValueInfo> RefEdgeList;
+  /// We use SmallVector<ValueInfo, 0> instead of std::vector<ValueInfo> for its
+  /// smaller memory footprint.
+  SmallVector<ValueInfo, 0> RefEdgeList;
 
 protected:
-  GlobalValueSummary(SummaryKind K, GVFlags Flags, std::vector<ValueInfo> Refs)
+  GlobalValueSummary(SummaryKind K, GVFlags Flags,
+                     SmallVectorImpl<ValueInfo> &&Refs)
       : Kind(K), Flags(Flags), RefEdgeList(std::move(Refs)) {
     assert((K != AliasKind || Refs.empty()) &&
            "Expect no references for AliasSummary");
@@ -641,7 +644,7 @@ class AliasSummary : public GlobalValueSummary {
 
 public:
   AliasSummary(GVFlags Flags)
-      : GlobalValueSummary(AliasKind, Flags, ArrayRef<ValueInfo>{}),
+      : GlobalValueSummary(AliasKind, Flags, SmallVector<ValueInfo, 0>{}),
         AliaseeSummary(nullptr) {}
 
   /// Check if this is an alias summary.
@@ -857,7 +860,7 @@ class FunctionSummary : public GlobalValueSummary {
             /*NotEligibleToImport=*/true, /*Live=*/true, /*IsLocal=*/false,
             /*CanAutoHide=*/false, GlobalValueSummary::ImportKind::Definition),
         /*NumInsts=*/0, FunctionSummary::FFlags{}, /*EntryCount=*/0,
-        std::vector<ValueInfo>(), std::move(Edges),
+        SmallVector<ValueInfo, 0>(), std::move(Edges),
         std::vector<GlobalValue::GUID>(),
         std::vector<FunctionSummary::VFuncId>(),
         std::vector<FunctionSummary::VFuncId>(),
@@ -913,7 +916,7 @@ class FunctionSummary : public GlobalValueSummary {
 
 public:
   FunctionSummary(GVFlags Flags, unsigned NumInsts, FFlags FunFlags,
-                  uint64_t EntryCount, std::vector<ValueInfo> Refs,
+                  uint64_t EntryCount, SmallVectorImpl<ValueInfo> &&Refs,
                   std::vector<EdgeTy> CGEdges,
                   std::vector<GlobalValue::GUID> TypeTests,
                   std::vector<VFuncId> TypeTestAssumeVCalls,
@@ -1166,7 +1169,7 @@ class GlobalVarSummary : public GlobalValueSummary {
   } VarFlags;
 
   GlobalVarSummary(GVFlags Flags, GVarFlags VarFlags,
-                   std::vector<ValueInfo> Refs)
+                   SmallVectorImpl<ValueInfo> &&Refs)
       : GlobalValueSummary(GlobalVarKind, Flags, std::move(Refs)),
         VarFlags(VarFlags) {}
 
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h b/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h
index 6cc533f043a51..ec2907ca7662e 100644
--- a/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h
+++ b/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h
@@ -216,7 +216,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
     }
     auto &Elem = V.try_emplace(KeyInt, /*IsAnalysis=*/false).first->second;
     for (auto &FSum : FSums) {
-      std::vector<ValueInfo> Refs;
+      SmallVector<ValueInfo, 0> Refs;
       Refs.reserve(FSum.Refs.size());
       for (auto &RefGUID : FSum.Refs) {
         auto It = V.try_emplace(RefGUID, /*IsAnalysis=*/false).first;
@@ -229,9 +229,9 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
               FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal,
               FSum.CanAutoHide,
               static_cast<GlobalValueSummary::ImportKind>(FSum.ImportType)),
-          /*NumInsts=*/0, FunctionSummary::FFlags{}, /*EntryCount=*/0, Refs,
-          ArrayRef<FunctionSummary::EdgeTy>{}, std::move(FSum.TypeTests),
-          std::move(FSum.TypeTestAssumeVCalls),
+          /*NumInsts=*/0, FunctionSummary::FFlags{}, /*EntryCount=*/0,
+          std::move(Refs), ArrayRef<FunctionSummary::EdgeTy>{},
+          std::move(FSum.TypeTests), std::move(FSum.TypeTestAssumeVCalls),
           std::move(FSum.TypeCheckedLoadVCalls),
           std::move(FSum.TypeTestAssumeConstVCalls),
           std::move(FSum.TypeCheckedLoadConstVCalls),
diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
index e9490ccba8215..39e7926ea43fe 100644
--- a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
+++ b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -99,10 +99,11 @@ extern cl::opt<bool> MemProfReportHintedSizes;
 // can only take an address of basic block located in the same function.
 // Set `RefLocalLinkageIFunc` to true if the analyzed value references a
 // local-linkage ifunc.
-static bool findRefEdges(ModuleSummaryIndex &Index, const User *CurUser,
-                         SetVector<ValueInfo, std::vector<ValueInfo>> &RefEdges,
-                         SmallPtrSet<const User *, 8> &Visited,
-                         bool &RefLocalLinkageIFunc) {
+static bool
+findRefEdges(ModuleSummaryIndex &Index, const User *CurUser,
+             SetVector<ValueInfo, SmallVector<ValueInfo, 0>> &RefEdges,
+             SmallPtrSet<const User *, 8> &Visited,
+             bool &RefLocalLinkageIFunc) {
   bool HasBlockAddress = false;
   SmallVector<const User *, 32> Worklist;
   if (Visited.insert(CurUser).second)
@@ -310,7 +311,7 @@ static void computeFunctionSummary(
   MapVector<ValueInfo, CalleeInfo, DenseMap<ValueInfo, unsigned>,
             std::vector<std::pair<ValueInfo, CalleeInfo>>>
       CallGraphEdges;
-  SetVector<ValueInfo, std::vector<ValueInfo>> RefEdges, LoadRefEdges,
+  SetVector<ValueInfo, SmallVector<ValueInfo, 0>> RefEdges, LoadRefEdges,
       StoreRefEdges;
   SetVector<GlobalValue::GUID, std::vector<GlobalValue::GUID>> TypeTests;
   SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
@@ -568,16 +569,17 @@ static void computeFunctionSummary(
   if (PSI->hasPartialSampleProfile() && ScalePartialSampleProfileWorkingSetSize)
     Index.addBlockCount(F.size());
 
-  std::vector<ValueInfo> Refs;
+  SmallVector<ValueInfo, 0> Refs;
   if (IsThinLTO) {
-    auto AddRefEdges = [&](const std::vector<const Instruction *> &Instrs,
-                           SetVector<ValueInfo, std::vector<ValueInfo>> &Edges,
-                           SmallPtrSet<const User *, 8> &Cache) {
-      for (const auto *I : Instrs) {
-        Cache.erase(I);
-        findRefEdges(Index, I, Edges, Cache, HasLocalIFuncCallOrRef);
-      }
-    };
+    auto AddRefEdges =
+        [&](const std::vector<const Instruction *> &Instrs,
+            SetVector<ValueInfo, SmallVector<ValueInfo, 0>> &Edges,
+            SmallPtrSet<const User *, 8> &Cache) {
+          for (const auto *I : Instrs) {
+            Cache.erase(I);
+            findRefEdges(Index, I, Edges, Cache, HasLocalIFuncCallOrRef);
+          }
+        };
 
     // By now we processed all instructions in a function, except
     // non-volatile loads and non-volatile value stores. Let's find
@@ -805,7 +807,7 @@ static void computeVariableSummary(ModuleSummaryIndex &Index,
                                    DenseSet<GlobalValue::GUID> &CantBePromoted,
                                    const Module &M,
                                    SmallVectorImpl<MDNode *> &Types) {
-  SetVector<ValueInfo, std::vector<ValueInfo>> RefEdges;
+  SetVector<ValueInfo, SmallVector<ValueInfo, 0>> RefEdges;
   SmallPtrSet<const User *, 8> Visited;
   bool RefLocalIFunc = false;
   bool HasBlockAddress =
@@ -961,7 +963,7 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex(
                         /* MayThrow */ true,
                         /* HasUnknownCall */ true,
                         /* MustBeUnreachable */ false},
-                    /*EntryCount=*/0, ArrayRef<ValueInfo>{},
+                    /*EntryCount=*/0, SmallVector<ValueInfo, 0>{},
                     ArrayRef<FunctionSummary::EdgeTy>{},
                     ArrayRef<GlobalValue::GUID>{},
                     ArrayRef<FunctionSummary::VFuncId>{},
@@ -978,7 +980,7 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex(
                     GlobalVarSummary::GVarFlags(
                         false, false, cast<GlobalVariable>(GV)->isConstant(),
                         GlobalObject::VCallVisibilityPublic),
-                    ArrayRef<ValueInfo>{});
+                    SmallVector<ValueInfo, 0>{});
             Index.addGlobalValueSummary(*GV, std::move(Summary));
           }
         });
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index f41907f035125..5964355fd26cc 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -9388,7 +9388,7 @@ bool LLParser::parseFunctionSummary(std::string Name, GlobalValue::GUID GUID,
   std::vector<FunctionSummary::EdgeTy> Calls;
   FunctionSummary::TypeIdInfo TypeIdInfo;
   std::vector<FunctionSummary::ParamAccess> ParamAccesses;
-  std::vector<ValueInfo> Refs;
+  SmallVector<ValueInfo, 0> Refs;
   std::vector<CallsiteInfo> Callsites;
   std::vector<AllocInfo> Allocs;
   // Default is all-zeros (conservative values).
@@ -9476,7 +9476,7 @@ bool LLParser::parseVariableSummary(std::string Name, GlobalValue::GUID GUID,
                                         /* WriteOnly */ false,
                                         /* Constant */ false,
                                         GlobalObject::VCallVisibilityPublic);
-  std::vector<ValueInfo> Refs;
+  SmallVector<ValueInfo, 0> Refs;
   VTableFuncList VTableFuncs;
   if (parseToken(lltok::colon, "expected ':' here") ||
       parseToken(lltok::lparen, "expected '(' here") ||
@@ -9982,7 +9982,7 @@ bool LLParser::parseOptionalParamAccesses(
 
 /// OptionalRefs
 ///   := 'refs' ':' '(' GVReference [',' GVReference]* ')'
-bool LLParser::parseOptionalRefs(std::vector<ValueInfo> &Refs) {
+bool LLParser::parseOptionalRefs(SmallVectorImpl<ValueInfo> &Refs) {
   assert(Lex.getKind() == lltok::kw_refs);
   Lex.Lex();
 
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 654be985a3229..3d87f1e339c85 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -985,7 +985,7 @@ class ModuleSummaryIndexBitcodeReader : public BitcodeReaderBase {
   Error parseValueSymbolTable(
       uint64_t Offset,
       DenseMap<unsigned, GlobalValue::LinkageTypes> &ValueIdToLinkageMap);
-  std::vector<ValueInfo> makeRefList(ArrayRef<uint64_t> Record);
+  SmallVector<ValueInfo, 0> makeRefList(ArrayRef<uint64_t> Record);
   std::vector<FunctionSummary::EdgeTy> makeCallList(ArrayRef<uint64_t> Record,
                                                     bool IsOldProfileFormat,
                                                     bool HasProfile,
@@ -7361,9 +7361,9 @@ Error ModuleSummaryIndexBitcodeReader::parseModule() {
   }
 }
 
-std::vector<ValueInfo>
+SmallVector<ValueInfo, 0>
 ModuleSummaryIndexBitcodeReader::makeRefList(ArrayRef<uint64_t> Record) {
-  std::vector<ValueInfo> Ret;
+  SmallVector<ValueInfo, 0> Ret;
   Ret.reserve(Record.size());
   for (uint64_t RefValueId : Record)
     Ret.push_back(std::get<0>(getValueInfoFromValueId(RefValueId)));
@@ -7508,7 +7508,7 @@ void ModuleSummaryIndexBitcodeReader::parseTypeIdCompatibleVtableSummaryRecord(
     parseTypeIdCompatibleVtableInfo(Record, Slot, TypeId);
 }
 
-static void setSpecialRefs(std::vector<ValueInfo> &Refs, unsigned ROCnt,
+static void setSpecialRefs(SmallVectorImpl<ValueInfo> &Refs, unsigned ROCnt,
                            unsigned WOCnt) {
   // Readonly and writeonly refs are in the end of the refs list.
   assert(ROCnt + WOCnt <= Refs.size());
@@ -7658,7 +7658,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
              "Record size inconsistent with number of references");
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       bool HasProfile = (BitCode == bitc::FS_PERMODULE_PROFILE);
       bool HasRelBF = (BitCode == bitc::FS_PERMODULE_RELBF);
@@ -7733,7 +7733,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
         GVF = getDecodedGVarFlags(Record[2]);
         RefArrayStart = 3;
       }
-      std::vector<ValueInfo> Refs =
+      SmallVector<ValueInfo, 0> Refs =
           makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
       auto FS =
           std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));
@@ -7754,7 +7754,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       unsigned RefListStartIndex = 4;
       unsigned VTableListStartIndex = RefListStartIndex + NumRefs;
       auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       VTableFuncList VTableFuncs;
       for (unsigned I = VTableListStartIndex, E = Record.size(); I != E; ++I) {
@@ -7815,7 +7815,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
              "Record size inconsistent with number of references");
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       bool HasProfile = (BitCode == bitc::FS_COMBINED_PROFILE);
       std::vector<FunctionSummary::EdgeTy> Edges = makeCallList(
@@ -7875,7 +7875,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
         GVF = getDecodedGVarFlags(Record[3]);
         RefArrayStart = 4;
       }
-      std::vector<ValueInfo> Refs =
+      SmallVector<ValueInfo, 0> Refs =
           makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
       auto FS =
           std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));