diff --git a/include/llvm/DebugInfo/CodeView/StreamRef.h b/include/llvm/DebugInfo/CodeView/StreamRef.h
index b581c120cca..22c4bdb5941 100644
--- a/include/llvm/DebugInfo/CodeView/StreamRef.h
+++ b/include/llvm/DebugInfo/CodeView/StreamRef.h
@@ -29,6 +29,8 @@ public:
 
   Error readBytes(uint32_t Offset, uint32_t Size,
                   ArrayRef<uint8_t> &Buffer) const override {
+    if (ViewOffset + Offset < Offset)
+      return make_error<CodeViewError>(cv_error_code::insufficient_buffer);
     if (Size + Offset > Length)
       return make_error<CodeViewError>(cv_error_code::insufficient_buffer);
     return Stream->readBytes(ViewOffset + Offset, Size, Buffer);
diff --git a/include/llvm/DebugInfo/PDB/Raw/IPDBFile.h b/include/llvm/DebugInfo/PDB/Raw/IPDBFile.h
index 717a7880f3c..fccea2ac247 100644
--- a/include/llvm/DebugInfo/PDB/Raw/IPDBFile.h
+++ b/include/llvm/DebugInfo/PDB/Raw/IPDBFile.h
@@ -33,8 +33,8 @@ public:
   virtual ArrayRef<support::ulittle32_t>
   getStreamBlockList(uint32_t StreamIndex) const = 0;
 
-  virtual ArrayRef<uint8_t> getBlockData(uint32_t BlockIndex,
-                                         uint32_t NumBytes) const = 0;
+  virtual Expected<ArrayRef<uint8_t>> getBlockData(uint32_t BlockIndex,
+                                                   uint32_t NumBytes) const = 0;
   virtual Error setBlockData(uint32_t BlockIndex, uint32_t Offset,
                              ArrayRef<uint8_t> Data) const = 0;
 };
diff --git a/include/llvm/DebugInfo/PDB/Raw/PDBFile.h b/include/llvm/DebugInfo/PDB/Raw/PDBFile.h
index f5aad723a77..a8e1dc5c307 100644
--- a/include/llvm/DebugInfo/PDB/Raw/PDBFile.h
+++ b/include/llvm/DebugInfo/PDB/Raw/PDBFile.h
@@ -84,8 +84,8 @@ public:
   getStreamBlockList(uint32_t StreamIndex) const override;
   size_t getFileSize() const;
 
-  ArrayRef<uint8_t> getBlockData(uint32_t BlockIndex,
-                                 uint32_t NumBytes) const override;
+  Expected<ArrayRef<uint8_t>> getBlockData(uint32_t BlockIndex,
+                                           uint32_t NumBytes) const override;
   Error setBlockData(uint32_t BlockIndex, uint32_t Offset,
                      ArrayRef<uint8_t> Data) const override;
 
diff --git a/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp b/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
index 3463871227b..92b2048c3c2 100644
--- a/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
+++ b/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
@@ -139,8 +139,10 @@ Error MappedBlockStream::readLongestContiguousChunk(
   uint32_t BlockSpan = Last - First + 1;
   uint32_t ByteSpan =
       BytesFromFirstBlock + (BlockSpan - 1) * Pdb.getBlockSize();
-  Buffer = Pdb.getBlockData(BlockList[First], Pdb.getBlockSize());
-  Buffer = Buffer.drop_front(OffsetInFirstBlock);
+  auto Result = Pdb.getBlockData(BlockList[First], Pdb.getBlockSize());
+  if (!Result)
+    return Result.takeError();
+  Buffer = Result->drop_front(OffsetInFirstBlock);
   Buffer = ArrayRef<uint8_t>(Buffer.data(), ByteSpan);
   return Error::success();
 }
@@ -173,8 +175,12 @@ bool MappedBlockStream::tryReadContiguously(uint32_t Offset, uint32_t Size,
   }
 
   uint32_t FirstBlockAddr = BlockList[BlockNum];
-  auto Data = Pdb.getBlockData(FirstBlockAddr, Pdb.getBlockSize());
-  Data = Data.drop_front(OffsetInBlock);
+  auto Result = Pdb.getBlockData(FirstBlockAddr, Pdb.getBlockSize());
+  if (!Result) {
+    consumeError(Result.takeError());
+    return false;
+  }
+  auto Data = Result->drop_front(OffsetInBlock);
   Buffer = ArrayRef<uint8_t>(Data.data(), Size);
   return true;
 }
@@ -197,8 +203,11 @@ Error MappedBlockStream::readBytes(uint32_t Offset,
   while (BytesLeft > 0) {
     uint32_t StreamBlockAddr = BlockList[BlockNum];
 
-    auto Data = Pdb.getBlockData(StreamBlockAddr, Pdb.getBlockSize());
+    auto Result = Pdb.getBlockData(StreamBlockAddr, Pdb.getBlockSize());
+    if (!Result)
+      return Result.takeError();
 
+    auto Data = *Result;
     const uint8_t *ChunkStart = Data.data() + OffsetInBlock;
     uint32_t BytesInChunk =
         std::min(BytesLeft, Pdb.getBlockSize() - OffsetInBlock);
diff --git a/lib/DebugInfo/PDB/Raw/PDBFile.cpp b/lib/DebugInfo/PDB/Raw/PDBFile.cpp
index 2d8e0d0ed91..b289fd0124b 100644
--- a/lib/DebugInfo/PDB/Raw/PDBFile.cpp
+++ b/lib/DebugInfo/PDB/Raw/PDBFile.cpp
@@ -73,13 +73,13 @@ PDBFile::getStreamBlockList(uint32_t StreamIndex) const {
 
 size_t PDBFile::getFileSize() const { return Buffer->getLength(); }
 
-ArrayRef<uint8_t> PDBFile::getBlockData(uint32_t BlockIndex,
-                                        uint32_t NumBytes) const {
+Expected<ArrayRef<uint8_t>> PDBFile::getBlockData(uint32_t BlockIndex,
+                                                  uint32_t NumBytes) const {
   uint64_t StreamBlockOffset = blockToOffset(BlockIndex, getBlockSize());
 
   ArrayRef<uint8_t> Result;
   if (auto EC = Buffer->readBytes(StreamBlockOffset, NumBytes, Result))
-    consumeError(std::move(EC));
+    return std::move(EC);
   return Result;
 }
 
@@ -460,4 +460,4 @@ Error PDBFile::commit() {
   }
 
   return Buffer->commit();
-}
\ No newline at end of file
+}
diff --git a/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp b/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
index e54f7ab1250..dd6fce23736 100644
--- a/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
+++ b/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
@@ -61,8 +61,8 @@ public:
       return ArrayRef<support::ulittle32_t>();
     return Blocks;
   }
-  ArrayRef<uint8_t> getBlockData(uint32_t BlockIndex,
-                                 uint32_t NumBytes) const override {
+  Expected<ArrayRef<uint8_t>> getBlockData(uint32_t BlockIndex,
+                                           uint32_t NumBytes) const override {
     return ArrayRef<uint8_t>(&Data[BlockIndex], NumBytes);
   }