diff --git a/compiler-rt/test/asan/TestCases/debug_double_free.cpp b/compiler-rt/test/asan/TestCases/debug_double_free.cpp
--- a/compiler-rt/test/asan/TestCases/debug_double_free.cpp
+++ b/compiler-rt/test/asan/TestCases/debug_double_free.cpp
@@ -37,7 +37,12 @@
   return 0;
 }
 
-void __asan_on_error() {
+// Required for dyld macOS 12.0+
+#if (__APPLE__)
+__attribute__((weak))
+#endif
+extern "C" void
+__asan_on_error() {
   int present = __asan_report_present();
   void *addr = __asan_get_report_address();
   const char *description = __asan_get_report_description();
diff --git a/compiler-rt/test/asan/TestCases/debug_report.cpp b/compiler-rt/test/asan/TestCases/debug_report.cpp
--- a/compiler-rt/test/asan/TestCases/debug_report.cpp
+++ b/compiler-rt/test/asan/TestCases/debug_report.cpp
@@ -37,7 +37,12 @@
 # define PTR_FMT "%p"
 #endif
 
-void __asan_on_error() {
+// Required for dyld macOS 12.0+
+#if (__APPLE__)
+__attribute__((weak))
+#endif
+extern "C" void
+__asan_on_error() {
   int present = __asan_report_present();
   void *pc = __asan_get_report_pc();
   void *bp = __asan_get_report_bp();
diff --git a/compiler-rt/test/asan/TestCases/default_options.cpp b/compiler-rt/test/asan/TestCases/default_options.cpp
--- a/compiler-rt/test/asan/TestCases/default_options.cpp
+++ b/compiler-rt/test/asan/TestCases/default_options.cpp
@@ -6,9 +6,13 @@
 
 const char *kAsanDefaultOptions = "verbosity=1 help=1";
 
-extern "C"
+// Required for dyld macOS 12.0+
+#if (__APPLE__)
+__attribute__((weak))
+#endif
 __attribute__((no_sanitize_address))
-const char *__asan_default_options() {
+extern "C" const char *
+__asan_default_options() {
   // CHECK: Available flags for AddressSanitizer:
   return kAsanDefaultOptions;
 }
diff --git a/compiler-rt/test/asan/TestCases/on_error_callback.cpp b/compiler-rt/test/asan/TestCases/on_error_callback.cpp
--- a/compiler-rt/test/asan/TestCases/on_error_callback.cpp
+++ b/compiler-rt/test/asan/TestCases/on_error_callback.cpp
@@ -6,8 +6,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-extern "C"
-void __asan_on_error() {
+// Required for dyld macOS 12.0+
+#if (__APPLE__)
+__attribute__((weak))
+#endif
+extern "C" void
+__asan_on_error() {
   fprintf(stderr, "__asan_on_error called\n");
   fflush(stderr);
 }
diff --git a/compiler-rt/test/ubsan/TestCases/Misc/monitor.cpp b/compiler-rt/test/ubsan/TestCases/Misc/monitor.cpp
--- a/compiler-rt/test/ubsan/TestCases/Misc/monitor.cpp
+++ b/compiler-rt/test/ubsan/TestCases/Misc/monitor.cpp
@@ -10,19 +10,21 @@
 
 #include <cstdio>
 
-extern "C" {
-void __ubsan_get_current_report_data(const char **OutIssueKind,
-                                     const char **OutMessage,
-                                     const char **OutFilename,
-                                     unsigned *OutLine, unsigned *OutCol,
-                                     char **OutMemoryAddr);
-
-// Override the definition of __ubsan_on_report from the runtime, just for
-// testing purposes.
-void __ubsan_on_report(void) {
+// Override __ubsan_on_report() from the runtime, just for testing purposes.
+// Required for dyld macOS 12.0+
+#if (__APPLE__)
+__attribute__((weak))
+#endif
+extern "C" void
+__ubsan_on_report(void) {
+  void __ubsan_get_current_report_data(
+      const char **OutIssueKind, const char **OutMessage,
+      const char **OutFilename, unsigned *OutLine, unsigned *OutCol,
+      char **OutMemoryAddr);
   const char *IssueKind, *Message, *Filename;
   unsigned Line, Col;
   char *Addr;
+
   __ubsan_get_current_report_data(&IssueKind, &Message, &Filename, &Line, &Col,
                                   &Addr);
 
@@ -33,7 +35,6 @@
 
   (void)Addr;
 }
-}
 
 int main() {
   char C = 3;