diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h b/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h
@@ -353,7 +353,7 @@
     DCHECK_GT(max_count, 0);
     TransferBatch *b = nullptr;
     constexpr uptr kShuffleArraySize = 48;
-    uptr shuffle_array[kShuffleArraySize];
+    UNINITIALIZED uptr shuffle_array[kShuffleArraySize];
     uptr count = 0;
     for (uptr i = region; i < region + n_chunks * size; i += size) {
       shuffle_array[count++] = i;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector.h b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector.h
@@ -241,7 +241,7 @@
                 int unique_tid) {
     ensureCurrentEpoch(dtls);
     uptr cur_idx = nodeToIndex(cur_node);
-    uptr added_edges[40];
+    UNINITIALIZED uptr added_edges[40];
     uptr n_added_edges = g_.addEdges(dtls->getLocks(current_epoch_), cur_idx,
                                      added_edges, ARRAY_SIZE(added_edges));
     for (uptr i = 0; i < n_added_edges; i++) {
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -215,6 +215,7 @@
 # define UNLIKELY(x) (x)
 # define PREFETCH(x) /* _mm_prefetch(x, _MM_HINT_NTA) */ (void)0
 # define WARN_UNUSED_RESULT
+# define UNINITIALIZED
 #else  // _MSC_VER
 # define ALWAYS_INLINE inline __attribute__((always_inline))
 # define ALIAS(x) __attribute__((alias(x)))
@@ -234,6 +235,11 @@
 #  define PREFETCH(x) __builtin_prefetch(x)
 # endif
 # define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+# if __has_attribute(uninitialized)
+#  define UNINITIALIZED __attribute__((uninitialized))
+# else  // __has_attribute(uninitialized)
+#  define UNINITIALIZED
+# endif  // __has_attribute(uninitialized)
 #endif  // _MSC_VER
 
 #if !defined(_MSC_VER) || defined(__clang__)
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
@@ -305,7 +305,7 @@
   // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
   // hand, the bigger the buffer is, the more the chance the error report will
   // fit into it.
-  char local_buffer[400];
+  UNINITIALIZED char local_buffer[400];
   SharedPrintfCodeNoBuffer(append_pid, local_buffer, ARRAY_SIZE(local_buffer),
                            format, args);
 }
diff --git a/compiler-rt/lib/tsan/rtl/tsan_flags.cpp b/compiler-rt/lib/tsan/rtl/tsan_flags.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_flags.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_flags.cpp
@@ -55,7 +55,7 @@
   SetCommonFlagsDefaults();
   {
     // Override some common flags defaults.
-    CommonFlags cf;
+    UNINITIALIZED CommonFlags cf;
     cf.CopyFrom(*common_flags());
     cf.external_symbolizer_path = GetEnv("TSAN_SYMBOLIZER_PATH");
     cf.allow_addr2line = true;
diff --git a/compiler-rt/lib/ubsan/ubsan_diag.cpp b/compiler-rt/lib/ubsan/ubsan_diag.cpp
--- a/compiler-rt/lib/ubsan/ubsan_diag.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_diag.cpp
@@ -47,7 +47,7 @@
   if (!flags()->print_stacktrace)
     return;
 
-  BufferedStackTrace stack;
+  UNINITIALIZED BufferedStackTrace stack;
   ubsan_GetStackTrace(&stack, kStackTraceMax, pc, bp, nullptr,
                 common_flags()->fast_unwind_on_fatal);
   stack.Print();
diff --git a/compiler-rt/lib/ubsan/ubsan_flags.cpp b/compiler-rt/lib/ubsan/ubsan_flags.cpp
--- a/compiler-rt/lib/ubsan/ubsan_flags.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_flags.cpp
@@ -48,7 +48,7 @@
 void InitializeFlags() {
   SetCommonFlagsDefaults();
   {
-    CommonFlags cf;
+    UNINITIALIZED CommonFlags cf;
     cf.CopyFrom(*common_flags());
     cf.external_symbolizer_path = GetFlag("UBSAN_SYMBOLIZER_PATH");
     OverrideCommonFlags(cf);