diff --git a/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp b/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp
@@ -46,8 +46,9 @@
   auto &M = Modules[NumModules++];
   uint8_t *AlignedStart = RoundUpByPage(Start);
   uint8_t *AlignedStop  = RoundDownByPage(Stop);
-  size_t NumFullPages = AlignedStop > AlignedStart ?
-                        (AlignedStop - AlignedStart) / PageSize() : 0;
+  size_t NumFullPages = AlignedStop > AlignedStart
+                            ? (AlignedStop - AlignedStart) / GetPageSizeCached()
+                            : 0;
   bool NeedFirst = Start < AlignedStart || !NumFullPages;
   bool NeedLast  = Stop > AlignedStop && AlignedStop >= AlignedStart;
   M.NumRegions = NumFullPages + NeedFirst + NeedLast;;
@@ -57,8 +58,8 @@
   size_t R = 0;
   if (NeedFirst)
     M.Regions[R++] = {Start, std::min(Stop, AlignedStart), true, false};
-  for (uint8_t *P = AlignedStart; P < AlignedStop; P += PageSize())
-    M.Regions[R++] = {P, P + PageSize(), true, true};
+  for (uint8_t *P = AlignedStart; P < AlignedStop; P += GetPageSizeCached())
+    M.Regions[R++] = {P, P + GetPageSizeCached(), true, true};
   if (NeedLast)
     M.Regions[R++] = {AlignedStop, Stop, true, false};
   assert(R == M.NumRegions);
diff --git a/compiler-rt/lib/fuzzer/FuzzerUtil.h b/compiler-rt/lib/fuzzer/FuzzerUtil.h
--- a/compiler-rt/lib/fuzzer/FuzzerUtil.h
+++ b/compiler-rt/lib/fuzzer/FuzzerUtil.h
@@ -15,6 +15,7 @@
 #include "FuzzerBuiltinsMsvc.h"
 #include "FuzzerCommand.h"
 #include "FuzzerDefs.h"
+#include <sys/auxv.h>
 
 namespace fuzzer {
 
@@ -94,16 +95,22 @@
   return static_cast<size_t>((sizeof(unsigned long long) * 8) - Clzll(X) - 1);
 }
 
-inline size_t PageSize() { return 4096; }
+inline size_t PageSizeCached;
+inline size_t GetPageSizeCached() {
+  if (!PageSizeCached)
+    PageSizeCached = getauxval(AT_PAGESZ);
+  return PageSizeCached;
+}
+
 inline uint8_t *RoundUpByPage(uint8_t *P) {
   uintptr_t X = reinterpret_cast<uintptr_t>(P);
-  size_t Mask = PageSize() - 1;
+  size_t Mask = GetPageSizeCached() - 1;
   X = (X + Mask) & ~Mask;
   return reinterpret_cast<uint8_t *>(X);
 }
 inline uint8_t *RoundDownByPage(uint8_t *P) {
   uintptr_t X = reinterpret_cast<uintptr_t>(P);
-  size_t Mask = PageSize() - 1;
+  size_t Mask = GetPageSizeCached() - 1;
   X = X & ~Mask;
   return reinterpret_cast<uint8_t *>(X);
 }