diff --git a/compiler-rt/lib/xray/CMakeLists.txt b/compiler-rt/lib/xray/CMakeLists.txt
index 673091807e348..c79b0b634ddf1 100644
--- a/compiler-rt/lib/xray/CMakeLists.txt
+++ b/compiler-rt/lib/xray/CMakeLists.txt
@@ -111,7 +111,7 @@ set(riscv64_SOURCES
   xray_trampoline_s390x.S
   )
 # Enable vector instructions in the assembly file.
-set_source_files_properties(xray_trampoline_s390x.S PROPERTIES COMPILE_FLAGS -mvx)
+set_source_files_properties(xray_trampoline_s390x.S PROPERTIES COMPILE_FLAGS -march=z13)
 
 set(XRAY_SOURCE_ARCHS
   arm
diff --git a/compiler-rt/lib/xray/xray_tsc.h b/compiler-rt/lib/xray/xray_tsc.h
index 118b6f00e33ea..c8a8b2f16fef8 100644
--- a/compiler-rt/lib/xray/xray_tsc.h
+++ b/compiler-rt/lib/xray/xray_tsc.h
@@ -96,6 +96,7 @@ namespace __xray {
 inline bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
 
 ALWAYS_INLINE uint64_t readTSC(uint8_t &CPU) XRAY_NEVER_INSTRUMENT {
+  CPU = 0;
 #if __has_builtin(__builtin_readcyclecounter)
   return __builtin_readcyclecounter();
 #else