diff -u a/googletest/include/gtest/gtest-printers.h b/googletest/include/gtest/gtest-printers.h
--- a/googletest/include/gtest/gtest-printers.h
+++ b/googletest/include/gtest/gtest-printers.h
@@ -479,6 +479,12 @@ inline void PrintTo(char8_t c, ::std::ostream* os) {
 }
 #endif
 
+// gcc/clang __{u,}int128_t
+#if defined(__SIZEOF_INT128__)
+GTEST_API_ void PrintTo(__uint128_t v, ::std::ostream* os);
+GTEST_API_ void PrintTo(__int128_t v, ::std::ostream* os);
+#endif  // __SIZEOF_INT128__
+
 // Overloads for C strings.
 GTEST_API_ void PrintTo(const char* s, ::std::ostream* os);
 inline void PrintTo(char* s, ::std::ostream* os) {
diff -u a/googletest/src/gtest-printers.cc b/googletest/src/gtest-printers.cc
--- a/googletest/src/gtest-printers.cc
+++ b/googletest/src/gtest-printers.cc
@@ -304,6 +304,51 @@ void PrintTo(char32_t c, ::std::ostream* os) {
       << static_cast<uint32_t>(c);
 }
 
+// gcc/clang __{u,}int128_t
+#if defined(__SIZEOF_INT128__)
+void PrintTo(__uint128_t v, ::std::ostream* os) {
+  if (v == 0) {
+    *os << "0";
+    return;
+  }
+
+  // Buffer large enough for ceil(log10(2^128))==39 and the null terminator
+  char buf[40];
+  char* p = buf + sizeof(buf);
+
+  // Some configurations have a __uint128_t, but no support for built in
+  // division. Do manual long division instead.
+
+  uint64_t high = static_cast<uint64_t>(v >> 64);
+  uint64_t low = static_cast<uint64_t>(v);
+
+  *--p = 0;
+  while (high != 0 || low != 0) {
+    uint64_t high_mod = high % 10;
+    high = high / 10;
+    // This is the long division algorithm specialized for a divisor of 10 and
+    // only two elements.
+    // Notable values:
+    //   2^64 / 10 == 1844674407370955161
+    //   2^64 % 10 == 6
+    const uint64_t carry = 6 * high_mod + low % 10;
+    low = low / 10 + high_mod * 1844674407370955161 + carry / 10;
+
+    char digit = static_cast<char>(carry % 10);
+    *--p = '0' + digit;
+  }
+  *os << p;
+}
+void PrintTo(__int128_t v, ::std::ostream* os) {
+  __uint128_t uv = static_cast<__uint128_t>(v);
+  if (v < 0) {
+    *os << "-";
+    uv = -uv;
+  }
+  PrintTo(uv, os);
+}
+#endif  // __SIZEOF_INT128__
+
 // Prints the given array of characters to the ostream.  CharType must be either
 // char, char8_t, char16_t, char32_t, or wchar_t.
 // The array starts at begin, the length is len, it may include '\0' characters