diff --git a/llvm/include/llvm/ProfileData/SampleProf.h b/llvm/include/llvm/ProfileData/SampleProf.h
--- a/llvm/include/llvm/ProfileData/SampleProf.h
+++ b/llvm/include/llvm/ProfileData/SampleProf.h
@@ -169,7 +169,7 @@
   uint64_t Size;
   // The index indicating the location of the current entry in
   // SectionHdrLayout table.
-  uint32_t LayoutIndex;
+  uint64_t LayoutIndex;
 };
 
 // Flags common for all sections are defined here. In SecHdrTableEntry::Flags,
diff --git a/llvm/include/llvm/ProfileData/SampleProfReader.h b/llvm/include/llvm/ProfileData/SampleProfReader.h
--- a/llvm/include/llvm/ProfileData/SampleProfReader.h
+++ b/llvm/include/llvm/ProfileData/SampleProfReader.h
@@ -170,7 +170,7 @@
 //            Number of samples to get to the desrired percentile.
 //
 // NAME TABLE
-//    SIZE (uint32_t)
+//    SIZE (uint64_t)
 //        Number of entries in the name table.
 //    NAMES
 //        A NUL-separated list of SIZE strings.
@@ -182,7 +182,7 @@
 //        NOTE: This field should only be present for top-level functions
 //              (i.e., not inlined into any caller). Inlined function calls
 //              have no prologue, so they don't need this.
-//    NAME_IDX (uint32_t)
+//    NAME_IDX (uint64_t)
 //        Index into the name table indicating the function name.
 //    SAMPLES (uint64_t)
 //        Total number of samples collected in this function.
@@ -204,7 +204,7 @@
 //            represent all the actual functions called at runtime.
 //          CALL_TARGETS
 //            A list of NUM_CALLS entries for each called function:
-//               NAME_IDX (uint32_t)
+//               NAME_IDX (uint64_t)
 //                  Index into the name table with the callee name.
 //               SAMPLES (uint64_t)
 //                  Number of samples collected at the call site.
@@ -623,7 +623,7 @@
   ErrorOr<StringRef> readString();
 
   /// Read the string index and check whether it overflows the table.
-  template <typename T> inline ErrorOr<uint32_t> readStringIndex(T &Table);
+  template <typename T> inline ErrorOr<size_t> readStringIndex(T &Table);
 
   /// Return true if we've reached the end of file.
   bool at_eof() const { return Data >= End; }
@@ -704,7 +704,7 @@
 
 protected:
   std::vector<SecHdrTableEntry> SecHdrTable;
-  std::error_code readSecHdrTableEntry(uint32_t Idx);
+  std::error_code readSecHdrTableEntry(uint64_t Idx);
   std::error_code readSecHdrTable();
 
   std::error_code readFuncMetadata(bool ProfileHasAttribute);
diff --git a/llvm/lib/ProfileData/SampleProfReader.cpp b/llvm/lib/ProfileData/SampleProfReader.cpp
--- a/llvm/lib/ProfileData/SampleProfReader.cpp
+++ b/llvm/lib/ProfileData/SampleProfReader.cpp
@@ -515,9 +515,9 @@
 }
 
 template <typename T>
-inline ErrorOr<uint32_t> SampleProfileReaderBinary::readStringIndex(T &Table) {
+inline ErrorOr<size_t> SampleProfileReaderBinary::readStringIndex(T &Table) {
   std::error_code EC;
-  auto Idx = readNumber<uint32_t>();
+  auto Idx = readNumber<size_t>();
   if (std::error_code EC = Idx.getError())
     return EC;
   if (*Idx >= Table.size())
@@ -696,7 +696,7 @@
 
 ErrorOr<SampleContextFrames>
 SampleProfileReaderExtBinaryBase::readContextFromTable() {
-  auto ContextIdx = readNumber<uint32_t>();
+  auto ContextIdx = readNumber<size_t>();
   if (std::error_code EC = ContextIdx.getError())
     return EC;
   if (*ContextIdx >= CSNameTable->size())
@@ -1066,11 +1066,11 @@
 }
 
 std::error_code SampleProfileReaderBinary::readNameTable() {
-  auto Size = readNumber<uint32_t>();
+  auto Size = readNumber<size_t>();
   if (std::error_code EC = Size.getError())
     return EC;
   NameTable.reserve(*Size + NameTable.size());
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (size_t I = 0; I < *Size; ++I) {
     auto Name(readString());
     if (std::error_code EC = Name.getError())
       return EC;
@@ -1121,14 +1121,14 @@
 // underlying raw function names that are stored in the name table, as well as
 // a callsite identifier that only makes sense for non-leaf frames.
 std::error_code SampleProfileReaderExtBinaryBase::readCSNameTableSec() {
-  auto Size = readNumber<uint32_t>();
+  auto Size = readNumber<size_t>();
   if (std::error_code EC = Size.getError())
     return EC;
 
   std::vector<SampleContextFrameVector> *PNameVec =
       new std::vector<SampleContextFrameVector>();
   PNameVec->reserve(*Size);
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (size_t I = 0; I < *Size; ++I) {
     PNameVec->emplace_back(SampleContextFrameVector());
     auto ContextSize = readNumber<uint32_t>();
     if (std::error_code EC = ContextSize.getError())
@@ -1249,7 +1249,7 @@
 }
 
 std::error_code
-SampleProfileReaderExtBinaryBase::readSecHdrTableEntry(uint32_t Idx) {
+SampleProfileReaderExtBinaryBase::readSecHdrTableEntry(uint64_t Idx) {
   SecHdrTableEntry Entry;
   auto Type = readUnencodedNumber<uint64_t>();
   if (std::error_code EC = Type.getError())