diff --git a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
index e9205c68c..4cd24822a 100644
--- a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -410,7 +410,11 @@ RecordDecl::field_iterator
 CGRecordLowering::accumulateBitFields(bool isNonVirtualBaseType,
                                       RecordDecl::field_iterator Field,
                                       RecordDecl::field_iterator FieldEnd) {
-  if (isDiscreteBitFieldABI()) {
+  // BACKPORT(#23007)
+  // If fine-grained-bitfield-accesses is enabled, we do not want to
+  // do the contiguous collection of bitfields.
+  if (isDiscreteBitFieldABI() &&
+      !Types.getCodeGenOpts().FineGrainedBitfieldAccesses) {
     // Run stores the first element of the current run of bitfields. FieldEnd is
     // used as a special value to note that we don't have a current run. A
     // bitfield run is a contiguous collection of bitfields that can be stored
@@ -517,7 +521,8 @@ CGRecordLowering::accumulateBitFields(bool isNonVirtualBaseType,
   // include padding when we've advanced to a subsequent bitfield run.
   RecordDecl::field_iterator Begin = FieldEnd;
   CharUnits BeginOffset;
-  uint64_t BitSizeSinceBegin;
+  // BACKPORT(#23007)
+  uint64_t BitSizeSinceBegin = 0;

   // The (non-inclusive) end of the largest acceptable access unit we've found
   // since Begin. If this is Begin, we're gathering the initial set of bitfields
@@ -526,7 +531,9 @@ CGRecordLowering::accumulateBitFields(bool isNonVirtualBaseType,
   // available padding characters.
   RecordDecl::field_iterator BestEnd = Begin;
   CharUnits BestEndOffset;
-  bool BestClipped; // Whether the representation must be in a byte array.
+  // BACKPORT(#23007)
+  // Whether the representation must be in a byte array.
+  bool BestClipped = false;

   for (;;) {
     // AtAlignedBoundary is true iff Field is the (potential) start of a new