diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -134,11 +134,7 @@
 
 // Platform-specific options.
 #if SANITIZER_MAC
-namespace __sanitizer {
-bool PlatformHasDifferentMemcpyAndMemmove();
-}
-#define PLATFORM_HAS_DIFFERENT_MEMCPY_AND_MEMMOVE \
-  (__sanitizer::PlatformHasDifferentMemcpyAndMemmove())
+#define PLATFORM_HAS_DIFFERENT_MEMCPY_AND_MEMMOVE false
 #elif SANITIZER_WINDOWS64
 #define PLATFORM_HAS_DIFFERENT_MEMCPY_AND_MEMMOVE false
 #else
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.h b/compiler-rt/lib/sanitizer_common/sanitizer_mac.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.h
@@ -33,9 +33,7 @@
 enum MacosVersion {
   MACOS_VERSION_UNINITIALIZED = 0,
   MACOS_VERSION_UNKNOWN,
-  MACOS_VERSION_LEOPARD,
-  MACOS_VERSION_SNOW_LEOPARD,
-  MACOS_VERSION_LION,
+  MACOS_VERSION_LION,  // macOS 10.7; oldest currently supported
   MACOS_VERSION_MOUNTAIN_LION,
   MACOS_VERSION_MAVERICKS,
   MACOS_VERSION_YOSEMITE,
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
@@ -629,8 +629,6 @@
   if (*p != '.') return MACOS_VERSION_UNKNOWN;
 
   switch (major) {
-    case 9: return MACOS_VERSION_LEOPARD;
-    case 10: return MACOS_VERSION_SNOW_LEOPARD;
     case 11: return MACOS_VERSION_LION;
     case 12: return MACOS_VERSION_MOUNTAIN_LION;
     case 13: return MACOS_VERSION_MAVERICKS;
@@ -662,15 +660,6 @@
   return result;
 }
 
-bool PlatformHasDifferentMemcpyAndMemmove() {
-  // On OS X 10.7 memcpy() and memmove() are both resolved
-  // into memmove$VARIANT$sse42.
-  // See also https://github.com/google/sanitizers/issues/34.
-  // TODO(glider): need to check dynamically that memcpy() and memmove() are
-  // actually the same function.
-  return GetMacosVersion() == MACOS_VERSION_SNOW_LEOPARD;
-}
-
 uptr GetRSS() {
   struct task_basic_info info;
   unsigned count = TASK_BASIC_INFO_COUNT;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc b/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
@@ -61,12 +61,10 @@
   malloc_zone_t *new_zone = (malloc_zone_t *)p;
   internal_memcpy(new_zone, &sanitizer_zone, sizeof(sanitizer_zone));
   new_zone->zone_name = NULL;  // The name will be changed anyway.
-  if (GetMacosVersion() >= MACOS_VERSION_LION) {
-    // Prevent the client app from overwriting the zone contents.
-    // Library functions that need to modify the zone will set PROT_WRITE on it.
-    // This matches the behavior of malloc_create_zone() on OSX 10.7 and higher.
-    mprotect(new_zone, allocated_size, PROT_READ);
-  }
+  // Prevent the client app from overwriting the zone contents.
+  // Library functions that need to modify the zone will set PROT_WRITE on it.
+  // This matches the behavior of malloc_create_zone() on OSX 10.7 and higher.
+  mprotect(new_zone, allocated_size, PROT_READ);
   // We're explicitly *NOT* registering the zone.
   return new_zone;
 }
@@ -75,11 +73,9 @@
   COMMON_MALLOC_ENTER();
   // We don't need to do anything here.  We're not registering new zones, so we
   // don't to unregister.  Just un-mprotect and free() the zone.
-  if (GetMacosVersion() >= MACOS_VERSION_LION) {
-    uptr page_size = GetPageSizeCached();
-    uptr allocated_size = RoundUpTo(sizeof(sanitizer_zone), page_size);
-    mprotect(zone, allocated_size, PROT_READ | PROT_WRITE);
-  }
+  uptr page_size = GetPageSizeCached();
+  uptr allocated_size = RoundUpTo(sizeof(sanitizer_zone), page_size);
+  mprotect(zone, allocated_size, PROT_READ | PROT_WRITE);
   if (zone->zone_name) {
     COMMON_MALLOC_FREE((void *)zone->zone_name);
   }