diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_flag_parser.h b/compiler-rt/lib/sanitizer_common/sanitizer_flag_parser.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_flag_parser.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_flag_parser.h
@@ -99,6 +99,15 @@
   return ok;
 }
 
+template <>
+inline bool FlagHandler<s64>::Parse(const char *value) {
+  const char *value_end;
+  *t_ = internal_simple_strtoll(value, &value_end, 10);
+  bool ok = *value_end == 0;
+  if (!ok) Printf("ERROR: Invalid value for s64 option: '%s'\n", value);
+  return ok;
+}
+
 class FlagParser {
   static const int kMaxFlags = 200;
   struct Flag {
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_flags_test.cc b/compiler-rt/lib/sanitizer_common/tests/sanitizer_flags_test.cc
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_flags_test.cc
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_flags_test.cc
@@ -16,6 +16,7 @@
 #include "sanitizer_common/sanitizer_allocator_internal.h"
 #include "gtest/gtest.h"
 
+#include <stdint.h>
 #include <string.h>
 
 namespace __sanitizer {
@@ -110,6 +111,21 @@
                "Invalid value for int option");
 }
 
+TEST(SanitizerCommon, LongLongIntFlags) {
+  s64 InitValue = -5;
+  s64 IntMin = INT64_MIN;
+  s64 IntMax = INT64_MAX;
+  TestFlag(InitValue, "flag_name=0", 0ll);
+  TestFlag(InitValue, "flag_name=42", 42ll);
+  TestFlag(InitValue, "flag_name=-42", -42ll);
+
+  TestFlag(InitValue, "flag_name=-9223372036854775808", IntMin);
+  TestFlag(InitValue, "flag_name=9223372036854775807", IntMax);
+
+  TestFlag(InitValue, "flag_name=-92233720368547758080000", IntMin);
+  TestFlag(InitValue, "flag_name=92233720368547758070000", IntMax);
+}
+
 TEST(SanitizerCommon, StrFlags) {
   TestFlag("zzz", 0, "zzz");
   TestFlag("zzz", "flag_name=", "");