Index: lib/builtins/fp_lib.h
===================================================================
--- lib/builtins/fp_lib.h
+++ lib/builtins/fp_lib.h
@@ -67,7 +67,7 @@
 #define significandBits 52
 
 static __inline int rep_clz(rep_t a) {
-#if defined __LP64__
+#if defined(__LP64__) || defined(_WIN64)
     return __builtin_clzl(a);
 #else
     if (a & REP_C(0xffffffff00000000))
Index: lib/builtins/int_lib.h
===================================================================
--- lib/builtins/int_lib.h
+++ lib/builtins/int_lib.h
@@ -88,6 +88,7 @@
 COMPILER_RT_ABI du_int __udivmoddi4(du_int a, du_int b, du_int* rem);
 #ifdef CRT_HAS_128BIT
 COMPILER_RT_ABI si_int __clzti2(ti_int a);
+COMPILER_RT_ABI ti_int __divti3(ti_int a, ti_int b);
 COMPILER_RT_ABI tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
 #endif
 
Index: lib/builtins/int_types.h
===================================================================
--- lib/builtins/int_types.h
+++ lib/builtins/int_types.h
@@ -60,7 +60,8 @@
     }s;
 } udwords;
 
-#if (defined(__LP64__) || defined(__wasm__) || defined(__mips64))
+#if (defined(__LP64__) || defined(__wasm__) || defined(__mips64) || \
+     (defined(_MSC_VER) && defined(_WIN64)))
 #define CRT_HAS_128BIT
 #endif
 
Index: lib/builtins/muloti4.c
===================================================================
--- lib/builtins/muloti4.c
+++ lib/builtins/muloti4.c
@@ -48,12 +48,12 @@
         return result;
     if (sa == sb)
     {
-        if (abs_a > MAX / abs_b)
+        if (abs_a > __divti3(MAX, abs_b))
             *overflow = 1;
     }
     else
     {
-        if (abs_a > MIN / -abs_b)
+        if (abs_a > __divti3(MIN, -abs_b))
             *overflow = 1;
     }
     return result;
Index: lib/builtins/mulvti3.c
===================================================================
--- lib/builtins/mulvti3.c
+++ lib/builtins/mulvti3.c
@@ -46,12 +46,12 @@
         return a * b;
     if (sa == sb)
     {
-        if (abs_a > MAX / abs_b)
+        if (abs_a > __divti3(MAX, abs_b))
             compilerrt_abort();
     }
     else
     {
-        if (abs_a > MIN / -abs_b)
+        if (abs_a > __divti3(MIN, -abs_b))
             compilerrt_abort();
     }
     return a * b;
Index: test/builtins/Unit/fixunsdfti_test.c
===================================================================
--- test/builtins/Unit/fixunsdfti_test.c
+++ test/builtins/Unit/fixunsdfti_test.c
@@ -99,13 +99,13 @@
         return 1;
 #endif
 
-    if (test__fixunsdfti(0x1.FFFFFFFFFFFFFp+63, 0xFFFFFFFFFFFFF800LL))
+    if (test__fixunsdfti(0x1.FFFFFFFFFFFFFp+63, 0xFFFFFFFFFFFFF800ULL))
         return 1;
-    if (test__fixunsdfti(0x1.0000000000000p+63, 0x8000000000000000LL))
+    if (test__fixunsdfti(0x1.0000000000000p+63, 0x8000000000000000ULL))
         return 1;
-    if (test__fixunsdfti(0x1.FFFFFFFFFFFFFp+62, 0x7FFFFFFFFFFFFC00LL))
+    if (test__fixunsdfti(0x1.FFFFFFFFFFFFFp+62, 0x7FFFFFFFFFFFFC00ULL))
         return 1;
-    if (test__fixunsdfti(0x1.FFFFFFFFFFFFEp+62, 0x7FFFFFFFFFFFF800LL))
+    if (test__fixunsdfti(0x1.FFFFFFFFFFFFEp+62, 0x7FFFFFFFFFFFF800ULL))
         return 1;
 
     if (test__fixunsdfti(0x1.FFFFFFFFFFFFFp+127, make_ti(0xFFFFFFFFFFFFF800LL, 0)))
Index: test/builtins/Unit/fixunssfti_test.c
===================================================================
--- test/builtins/Unit/fixunssfti_test.c
+++ test/builtins/Unit/fixunssfti_test.c
@@ -87,13 +87,13 @@
         return 1;
 #endif
 
-    if (test__fixunssfti(0x1.FFFFFEp+63F, 0xFFFFFF0000000000LL))
+    if (test__fixunssfti(0x1.FFFFFEp+63F, 0xFFFFFF0000000000ULL))
         return 1;
-    if (test__fixunssfti(0x1.000000p+63F, 0x8000000000000000LL))
+    if (test__fixunssfti(0x1.000000p+63F, 0x8000000000000000ULL))
         return 1;
-    if (test__fixunssfti(0x1.FFFFFEp+62F, 0x7FFFFF8000000000LL))
+    if (test__fixunssfti(0x1.FFFFFEp+62F, 0x7FFFFF8000000000ULL))
         return 1;
-    if (test__fixunssfti(0x1.FFFFFCp+62F, 0x7FFFFF0000000000LL))
+    if (test__fixunssfti(0x1.FFFFFCp+62F, 0x7FFFFF0000000000ULL))
         return 1;
 
     if (test__fixunssfti(0x1.FFFFFEp+127F, make_ti(0xFFFFFF0000000000LL, 0)))
Index: test/builtins/Unit/fixunsxfti_test.c
===================================================================
--- test/builtins/Unit/fixunsxfti_test.c
+++ test/builtins/Unit/fixunsxfti_test.c
@@ -55,7 +55,7 @@
 
 int main()
 {
-#ifdef CRT_HAS_128BIT
+#if defined(CRT_HAS_128BIT) && !defined(_MSC_VER)
     if (test__fixunsxfti(0.0, 0))
         return 1;
 
Index: test/builtins/Unit/fixxfti_test.c
===================================================================
--- test/builtins/Unit/fixxfti_test.c
+++ test/builtins/Unit/fixxfti_test.c
@@ -53,7 +53,7 @@
 
 int main()
 {
-#ifdef CRT_HAS_128BIT
+#if defined(CRT_HAS_128BIT) && !defined(_MSC_VER)
     if (test__fixxfti(0.0, 0))
         return 1;
 
Index: test/builtins/Unit/floattixf_test.c
===================================================================
--- test/builtins/Unit/floattixf_test.c
+++ test/builtins/Unit/floattixf_test.c
@@ -51,7 +51,7 @@
 
 int main()
 {
-#ifdef CRT_HAS_128BIT
+#if defined(CRT_HAS_128BIT) && !defined(_MSC_VER)
     if (test__floattixf(0, 0.0))
         return 1;
 
Index: test/builtins/Unit/floatuntisf_test.c
===================================================================
--- test/builtins/Unit/floatuntisf_test.c
+++ test/builtins/Unit/floatuntisf_test.c
@@ -92,9 +92,9 @@
     if (test__floatuntisf(0x0007FB72E4000000LL, 0x1.FEDCB9p+50F))
         return 1;
 
-    if (test__floatuntisf(0xFFFFFFFFFFFFFFFELL, 0x1p+64F))
+    if (test__floatuntisf(0xFFFFFFFFFFFFFFFEULL, 0x1p+64F))
         return 1;
-    if (test__floatuntisf(0xFFFFFFFFFFFFFFFFLL, 0x1p+64F))
+    if (test__floatuntisf(0xFFFFFFFFFFFFFFFFULL, 0x1p+64F))
         return 1;
 
     if (test__floatuntisf(0x0007FB72E8000000LL, 0x1.FEDCBAp+50F))
Index: test/builtins/Unit/floatuntixf_test.c
===================================================================
--- test/builtins/Unit/floatuntixf_test.c
+++ test/builtins/Unit/floatuntixf_test.c
@@ -51,7 +51,7 @@
 
 int main()
 {
-#ifdef CRT_HAS_128BIT
+#if defined(CRT_HAS_128BIT) && !defined(_MSC_VER)
     if (test__floatuntixf(0, 0.0))
         return 1;
 
Index: test/builtins/Unit/modti3_test.c
===================================================================
--- test/builtins/Unit/modti3_test.c
+++ test/builtins/Unit/modti3_test.c
@@ -63,17 +63,17 @@
     if (test__modti3(-5, -3, -2))
         return 1;
 
-    if (test__modti3(0x8000000000000000LL, 1, 0x0LL))
+    if (test__modti3(0x8000000000000000ULL, 1, 0x0LL))
         return 1;
-    if (test__modti3(0x8000000000000000LL, -1, 0x0LL))
+    if (test__modti3(0x8000000000000000ULL, -1, 0x0LL))
         return 1;
-    if (test__modti3(0x8000000000000000LL, 2, 0x0LL))
+    if (test__modti3(0x8000000000000000ULL, 2, 0x0LL))
         return 1;
-    if (test__modti3(0x8000000000000000LL, -2, 0x0LL))
+    if (test__modti3(0x8000000000000000ULL, -2, 0x0LL))
         return 1;
-    if (test__modti3(0x8000000000000000LL, 3, 2))
+    if (test__modti3(0x8000000000000000ULL, 3, 2))
         return 1;
-    if (test__modti3(0x8000000000000000LL, -3, 2))
+    if (test__modti3(0x8000000000000000ULL, -3, 2))
         return 1;
 
     if (test__modti3(make_ti(0x8000000000000000LL, 0), 1, 0x0LL))