Index: compiler-rt/trunk/lib/xray/xray_fdr_logging.cc
===================================================================
--- compiler-rt/trunk/lib/xray/xray_fdr_logging.cc
+++ compiler-rt/trunk/lib/xray/xray_fdr_logging.cc
@@ -120,7 +120,8 @@
   XRayFileHeader Header;
   Header.Version = 1;
   Header.Type = FileTypes::FDR_LOG;
-  Header.CycleFrequency = getTSCFrequency();
+  Header.CycleFrequency = probeRequiredCPUFeatures()
+                          ? getTSCFrequency() : __xray::NanosecondsPerSecond;
   // FIXME: Actually check whether we have 'constant_tsc' and 'nonstop_tsc'
   // before setting the values in the header.
   Header.ConstantTSC = 1;
Index: compiler-rt/trunk/lib/xray/xray_fdr_logging_impl.h
===================================================================
--- compiler-rt/trunk/lib/xray/xray_fdr_logging_impl.h
+++ compiler-rt/trunk/lib/xray/xray_fdr_logging_impl.h
@@ -423,7 +423,9 @@
       return;
     }
 
-    uint64_t CycleFrequency = getTSCFrequency();
+    uint64_t CycleFrequency = probeRequiredCPUFeatures()
+                              ? getTSCFrequency()
+                              : __xray::NanosecondsPerSecond;
     NumberOfTicksThreshold = CycleFrequency *
                              flags()->xray_fdr_log_func_duration_threshold_us /
                              1000000;