diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
@@ -117,6 +117,7 @@
 // unaccessible memory.
 bool MprotectNoAccess(uptr addr, uptr size);
 bool MprotectReadOnly(uptr addr, uptr size);
+bool MprotectReadWrite(uptr addr, uptr size);
 
 void MprotectMallocZones(void *addr, int prot);
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_fuchsia.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_fuchsia.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_fuchsia.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_fuchsia.cpp
@@ -285,6 +285,12 @@
          ZX_OK;
 }
 
+bool MprotectReadWrite(uptr addr, uptr size) {
+  return _zx_vmar_protect(_zx_vmar_root_self(),
+                          ZX_VM_PERM_READ | ZX_VM_PERM_WRITE, addr,
+                          size) == ZX_OK;
+}
+
 void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
                                    const char *mem_type) {
   CHECK_GE(size, GetPageSize());
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
@@ -154,6 +154,10 @@
   return 0 == internal_mprotect((void *)addr, size, PROT_READ);
 }
 
+bool MprotectReadWrite(uptr addr, uptr size) {
+  return 0 == internal_mprotect((void *)addr, size, PROT_READ | PROT_WRITE);
+}
+
 #if !SANITIZER_APPLE
 void MprotectMallocZones(void *addr, int prot) {}
 #endif
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
@@ -362,6 +362,11 @@
   return VirtualProtect((LPVOID)addr, size, PAGE_READONLY, &old_protection);
 }
 
+bool MprotectReadWrite(uptr addr, uptr size) {
+  DWORD old_protection;
+  return VirtualProtect((LPVOID)addr, size, PAGE_READWRITE, &old_protection);
+}
+
 void ReleaseMemoryPagesToOS(uptr beg, uptr end) {
   uptr beg_aligned = RoundDownTo(beg, GetPageSizeCached()),
        end_aligned = RoundDownTo(end, GetPageSizeCached());