diff --git a/include/llvm/Support/MathExtras.h b/include/llvm/Support/MathExtras.h
index 6740786..d0b3477 100644
--- a/include/llvm/Support/MathExtras.h
+++ b/include/llvm/Support/MathExtras.h
@@ -76,6 +76,12 @@ inline bool isUIntN(unsigned N, uint64_t x) {
   return x == (x & (~0ULL >> (64 - N)));
 }
 
+/// isIIntN - Checks if an signed integer fits into the given (dynamic)
+/// bit width.
+inline bool isIntN(unsigned N, int64_t x) {
+  return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
+}
+
 /// isMask_32 - This function returns true if the argument is a sequence of ones
 /// starting at the least significant bit with the remainder zero (32 bit
 /// version).   Ex. isMask_32(0x0000FFFFU) == true.
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 6f9692d..fc7a754 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -48,7 +48,8 @@ void MCStreamer::EmitDwarfSetLineAddr(int64_t LineDelta,
 void MCStreamer::EmitIntValue(uint64_t Value, unsigned Size,
                               unsigned AddrSpace) {
   assert(Size <= 8 && "Invalid size");
-  assert(!(Size == 1 && (signed)Value > 255) && "Invalid size");
+  unsigned Bits = 8 * Size;
+  assert((isUIntN(Bits, Value) || isIntN(Bits, Value)) && "Invalid size");
   char buf[8];
   // FIXME: Endianness assumption.
   for (unsigned i = 0; i != Size; ++i)
