diff --git a/builtins/util.m4 b/builtins/util.m4
index 4bdc501b..a991ae09 100644
--- a/builtins/util.m4
+++ b/builtins/util.m4
@@ -50,11 +50,11 @@ define(`MASK_HIGH_BIT_ON',
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; vector convertation utilities
-;; convert 1-wide vector into 8-wide vector
+;; convert vector of one width into vector of other width
 ;;
 ;; $1: vector element type
-;; $2: 1-wide vector
-;; $3: 8-wide vector
+;; $2: vector of the first width
+;; $3: vector of the second width
 
 
 define(`convert1to8', `
@@ -129,13 +129,6 @@ define(`convert16to32', `
               i32 undef, i32 undef, i32 undef, i32 undef>
 ')
 
-;; convert 4-wide vector into 8-wide vector
-;;
-;; $1: vector element type
-;; $2: 8-wide vector
-;; $3: 1-wide vector
-
-
 define(`convert8to1', `
   $3 = shufflevector <8 x $1> $2, <8 x $1> undef,
     <1 x i32> <i32 0>
@@ -212,7 +205,6 @@ ifelse(WIDTH,  `4', `<$1 $2, $1 $2, $1 $2, $1 $2>',
 ;; $1: {add,sub} (used in constructing function names)
                         
 define(`saturation_arithmetic_novec_universal', `
-declare <16 x i8> @llvm.x86.sse2.p$1s.b(<16 x i8>, <16 x i8>) nounwind readnone
 define <WIDTH x i8> @__p$1s_vi8(<WIDTH x i8>, <WIDTH x i8>) {
   %v0_i16 = sext <WIDTH x i8> %0 to <WIDTH x i16>
   %v1_i16 = sext <WIDTH x i8> %1 to <WIDTH x i16>
@@ -225,7 +217,6 @@ define <WIDTH x i8> @__p$1s_vi8(<WIDTH x i8>, <WIDTH x i8>) {
   ret <WIDTH x i8> %ret
 }
 
-declare <8 x i16> @llvm.x86.sse2.p$1s.w(<8 x i16>, <8 x i16>) nounwind readnone
 define <WIDTH x i16> @__p$1s_vi16(<WIDTH x i16>, <WIDTH x i16>) {
   %v0_i32 = sext <WIDTH x i16> %0 to <WIDTH x i32>
   %v1_i32 = sext <WIDTH x i16> %1 to <WIDTH x i32>
@@ -238,7 +229,6 @@ define <WIDTH x i16> @__p$1s_vi16(<WIDTH x i16>, <WIDTH x i16>) {
   ret <WIDTH x i16> %ret
 }
 
-declare <16 x i8> @llvm.x86.sse2.p$1us.b(<16 x i8>, <16 x i8>) nounwind readnone
 define <WIDTH x i8> @__p$1us_vi8(<WIDTH x i8>, <WIDTH x i8>) {
   %v0_i16 = zext <WIDTH x i8> %0 to <WIDTH x i16>
   %v1_i16 = zext <WIDTH x i8> %1 to <WIDTH x i16>
@@ -251,7 +241,6 @@ define <WIDTH x i8> @__p$1us_vi8(<WIDTH x i8>, <WIDTH x i8>) {
   ret <WIDTH x i8> %ret
 }
 
-declare <8 x i16> @llvm.x86.sse2.p$1us.w(<8 x i16>, <8 x i16>) nounwind readnone
 define <WIDTH x i16> @__p$1us_vi16(<WIDTH x i16>, <WIDTH x i16>) {
   %v0_i32 = zext <WIDTH x i16> %0 to <WIDTH x i32>
   %v1_i32 = zext <WIDTH x i16> %1 to <WIDTH x i32>
diff --git a/stdlib.ispc b/stdlib.ispc
index f977abf8..9bb13f4e 100644
--- a/stdlib.ispc
+++ b/stdlib.ispc
@@ -58,15 +58,6 @@
 #endif
 
 /* Limits of integral types. */
-#ifndef INT8_MIN
-#define INT8_MIN               (-128)
-#endif
-#ifndef INT16_MIN
-#define INT16_MIN              (-32768)
-#endif
-#ifndef INT32_MIN
-#define INT32_MIN              (-2147483648)
-#endif
 #ifndef INT8_MAX
 #define INT8_MAX               (127)
 #endif
@@ -76,6 +67,9 @@
 #ifndef INT32_MAX
 #define INT32_MAX              (2147483647)
 #endif
+#ifndef INT64_MAX
+#define INT64_MAX              (9223372036854775807)
+#endif
 #ifndef UINT8_MAX
 #define UINT8_MAX              (255)
 #endif
@@ -85,6 +79,21 @@
 #ifndef UINT32_MAX
 #define UINT32_MAX             (4294967295)
 #endif
+#ifndef UINT64_MAX
+#define UINT64_MAX             (18446744073709551615)
+#endif
+#ifndef INT8_MIN
+#define INT8_MIN               (-INT8_MAX - 1)
+#endif
+#ifndef INT16_MIN
+#define INT16_MIN              (-INT16_MAX - 1)
+#endif
+#ifndef INT32_MIN
+#define INT32_MIN              (-INT32_MAX - 1)
+#endif
+#ifndef INT64_MIN
+#define INT64_MIN              (-INT64_MAX - 1)
+#endif
 ///////////////////////////////////////////////////////////////////////////
 // Low level primitives