diff --git a/compiler-rt/lib/scudo/standalone/memtag.h b/compiler-rt/lib/scudo/standalone/memtag.h
--- a/compiler-rt/lib/scudo/standalone/memtag.h
+++ b/compiler-rt/lib/scudo/standalone/memtag.h
@@ -41,6 +41,8 @@
 
 inline constexpr bool archSupportsMemoryTagging() { return false; }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-noreturn"
 inline uptr archMemoryTagGranuleSize() {
   UNREACHABLE("memory tagging not supported");
 }
@@ -54,6 +56,7 @@
   (void)Ptr;
   UNREACHABLE("memory tagging not supported");
 }
+#pragma clang diagnostic pop
 
 #endif
 
@@ -109,6 +112,8 @@
 
 inline bool systemSupportsMemoryTagging() { return false; }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-noreturn"
 inline bool systemDetectsMemoryTagFaultsTestOnly() {
   UNREACHABLE("memory tagging not supported");
 }
@@ -116,6 +121,7 @@
 inline void enableSystemMemoryTaggingTestOnly() {
   UNREACHABLE("memory tagging not supported");
 }
+#pragma clang diagnostic pop
 
 #endif // SCUDO_LINUX
 
@@ -255,6 +261,8 @@
 
 #else
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-noreturn"
 inline bool systemSupportsMemoryTagging() {
   UNREACHABLE("memory tagging not supported");
 }
@@ -298,6 +306,7 @@
   (void)Ptr;
   UNREACHABLE("memory tagging not supported");
 }
+#pragma clang diagnostic pop
 
 #endif
 
diff --git a/compiler-rt/lib/scudo/standalone/secondary.h b/compiler-rt/lib/scudo/standalone/secondary.h
--- a/compiler-rt/lib/scudo/standalone/secondary.h
+++ b/compiler-rt/lib/scudo/standalone/secondary.h
@@ -219,7 +219,7 @@
     const u32 MaxCount = atomic_load_relaxed(&MaxEntriesCount);
     bool Found = false;
     CachedBlock Entry;
-    uptr HeaderPos;
+    uptr HeaderPos = 0;
     {
       ScopedLock L(Mutex);
       if (EntriesCount == 0)