diff --git a/llvm/include/llvm/Support/ConstantRange.h b/llvm/include/llvm/Support/ConstantRange.h
index 29086b2ac4f2..2af2cf61eaea 100644
--- a/llvm/include/llvm/Support/ConstantRange.h
+++ b/llvm/include/llvm/Support/ConstantRange.h
@@ -92,6 +92,11 @@ public:
   ///
   bool isWrappedSet() const;
 
+  /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
+  /// its bitwidth, for example: i8 [120, 140).
+  ///
+  bool isSignWrappedSet() const;
+
   /// contains - Return true if the specified value is in the set.
   ///
   bool contains(const APInt &Val) const;
diff --git a/llvm/lib/Support/ConstantRange.cpp b/llvm/lib/Support/ConstantRange.cpp
index 8ef3785f5331..defb8189b628 100644
--- a/llvm/lib/Support/ConstantRange.cpp
+++ b/llvm/lib/Support/ConstantRange.cpp
@@ -115,6 +115,14 @@ bool ConstantRange::isWrappedSet() const {
   return Lower.ugt(Upper);
 }
 
+/// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
+/// its bitwidth, for example: i8 [120, 140).
+///
+bool ConstantRange::isSignWrappedSet() const {
+  return contains(APInt::getSignedMaxValue(getBitWidth())) &&
+         contains(APInt::getSignedMinValue(getBitWidth()));
+}
+
 /// getSetSize - Return the number of elements in this set.
 ///
 APInt ConstantRange::getSetSize() const {
@@ -408,10 +416,12 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
 /// correspond to the possible range of values as if the source range had been
 /// zero extended.
 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
+  if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
+
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
-  if (isFullSet())
-    // Change a source full set into [0, 1 << 8*numbytes)
+  if (isFullSet() || isWrappedSet())
+    // Change into [0, 1 << src bit width)
     return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
 
   APInt L = Lower; L.zext(DstTySize);
@@ -424,9 +434,11 @@ ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
 /// correspond to the possible range of values as if the source range had been
 /// sign extended.
 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
+  if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
+
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
-  if (isFullSet()) {
+  if (isFullSet() || isSignWrappedSet()) {
     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
   }
diff --git a/llvm/unittests/Support/ConstantRangeTest.cpp b/llvm/unittests/Support/ConstantRangeTest.cpp
index 091ecd4aadeb..1cedeae50afd 100644
--- a/llvm/unittests/Support/ConstantRangeTest.cpp
+++ b/llvm/unittests/Support/ConstantRangeTest.cpp
@@ -146,6 +146,22 @@ TEST_F(ConstantRangeTest, GetMinsAndMaxes) {
             APInt(4, 7));
 }
 
+TEST_F(ConstantRangeTest, SignWrapped) {
+  EXPECT_TRUE(Full.isSignWrappedSet());
+  EXPECT_FALSE(Empty.isSignWrappedSet());
+  EXPECT_FALSE(One.isSignWrappedSet());
+  EXPECT_FALSE(Some.isSignWrappedSet());
+  EXPECT_TRUE(Wrap.isSignWrappedSet());
+
+  EXPECT_FALSE(ConstantRange(APInt(8, 127), APInt(8, 128)).isSignWrappedSet());
+  EXPECT_TRUE(ConstantRange(APInt(8, 127), APInt(8, 129)).isSignWrappedSet());
+  EXPECT_FALSE(ConstantRange(APInt(8, 128), APInt(8, 129)).isSignWrappedSet());
+  EXPECT_TRUE(ConstantRange(APInt(8, 10), APInt(8, 9)).isSignWrappedSet());
+  EXPECT_TRUE(ConstantRange(APInt(8, 10), APInt(8, 250)).isSignWrappedSet());
+  EXPECT_FALSE(ConstantRange(APInt(8, 250), APInt(8, 10)).isSignWrappedSet());
+  EXPECT_FALSE(ConstantRange(APInt(8, 250), APInt(8, 251)).isSignWrappedSet());
+}
+
 TEST_F(ConstantRangeTest, Trunc) {
   ConstantRange TFull = Full.truncate(10);
   ConstantRange TEmpty = Empty.truncate(10);
@@ -171,8 +187,7 @@ TEST_F(ConstantRangeTest, ZExt) {
                                 APInt(One.getUpper()).zext(20)));
   EXPECT_EQ(ZSome, ConstantRange(APInt(Some.getLower()).zext(20),
                                  APInt(Some.getUpper()).zext(20)));
-  EXPECT_EQ(ZWrap, ConstantRange(APInt(Wrap.getLower()).zext(20),
-                                 APInt(Wrap.getUpper()).zext(20)));
+  EXPECT_EQ(ZWrap, ConstantRange(APInt(20, 0), APInt(20, 0x10000)));
 }
 
 TEST_F(ConstantRangeTest, SExt) {
@@ -188,8 +203,11 @@ TEST_F(ConstantRangeTest, SExt) {
                                 APInt(One.getUpper()).sext(20)));
   EXPECT_EQ(SSome, ConstantRange(APInt(Some.getLower()).sext(20),
                                  APInt(Some.getUpper()).sext(20)));
-  EXPECT_EQ(SWrap, ConstantRange(APInt(Wrap.getLower()).sext(20),
-                                 APInt(Wrap.getUpper()).sext(20)));
+  EXPECT_EQ(SWrap, ConstantRange(APInt(20, (uint64_t)INT16_MIN, true),
+                                 APInt(20, INT16_MAX + 1, true)));
+
+  EXPECT_EQ(ConstantRange(APInt(8, 120), APInt(8, 140)).signExtend(16),
+            ConstantRange(APInt(16, -128), APInt(16, 128)));
 }
 
 TEST_F(ConstantRangeTest, IntersectWith) {