diff --git a/llvm/lib/Transforms/Instrumentation/RealtimeSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/RealtimeSanitizer.cpp
index 5ef6ffb58a7c1..adb0e518c6074 100644
--- a/llvm/lib/Transforms/Instrumentation/RealtimeSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/RealtimeSanitizer.cpp
@@ -61,23 +61,21 @@ static void insertCallAtAllFunctionExitPoints(Function &Fn,
       insertCallBeforeInstruction(Fn, I, InsertFnName, FunctionArgs);
 }
 
-static PreservedAnalyses rtsanPreservedCFGAnalyses() {
-  PreservedAnalyses PA;
-  PA.preserveSet<CFGAnalyses>();
-  return PA;
-}
+static void runSanitizeRealtime(Function &Fn) {
+  if (Fn.empty())
+    return;
 
-static PreservedAnalyses runSanitizeRealtime(Function &Fn) {
   insertCallAtFunctionEntryPoint(Fn, "__rtsan_realtime_enter", {});
   insertCallAtAllFunctionExitPoints(Fn, "__rtsan_realtime_exit", {});
-  return rtsanPreservedCFGAnalyses();
 }
 
-static PreservedAnalyses runSanitizeRealtimeBlocking(Function &Fn) {
+static void runSanitizeRealtimeBlocking(Function &Fn) {
+  if (Fn.empty())
+    return;
+
   IRBuilder<> Builder(&Fn.front().front());
   Value *Name = Builder.CreateGlobalString(demangle(Fn.getName()));
   insertCallAtFunctionEntryPoint(Fn, "__rtsan_notify_blocking_call", {Name});
-  return rtsanPreservedCFGAnalyses();
 }
 
 PreservedAnalyses RealtimeSanitizerPass::run(Module &M,
diff --git a/llvm/test/Instrumentation/RealtimeSanitizer/rtsan_attrib_declare.ll b/llvm/test/Instrumentation/RealtimeSanitizer/rtsan_attrib_declare.ll
new file mode 100644
index 0000000000000..a5336b9e9e491
--- /dev/null
+++ b/llvm/test/Instrumentation/RealtimeSanitizer/rtsan_attrib_declare.ll
@@ -0,0 +1,12 @@
+; RUN: opt < %s -passes='rtsan' -S | FileCheck %s
+
+declare void @declared_realtime_function() sanitize_realtime #0
+
+declare void @declared_blocking_function() sanitize_realtime_blocking #0
+
+; RealtimeSanitizer pass should ignore attributed functions that are just declarations
+; CHECK: declared_realtime_function
+; CHECK-EMPTY:
+; CHECK: declared_blocking_function
+; CHECK-EMPTY:
+