Index: include/llvm/IR/ConstantRange.h
===================================================================
--- include/llvm/IR/ConstantRange.h
+++ include/llvm/IR/ConstantRange.h
@@ -82,6 +82,17 @@
   static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
                                                 const ConstantRange &Other);
 
+  /// Return the largest range containing all X such that "X BinOpC C" does not
+  /// wrap (overflow).
+  ///
+  /// Example:
+  ///  typedef OverflowingBinaryOperator OBO;
+  ///  makeNoWrapRegion(Add, i8 1, OBO::NoSignedWrap) == [-128, 127)
+  ///  makeNoWrapRegion(Add, i8 1, OBO::UnsignedWrap) == [0, -1)
+  ///  makeNoWrapRegion(Add, i8 0, OBO::NoUnsignedWrap) == Full Set
+  static ConstantRange makeNoWrapRegion(Instruction::BinaryOps BinOp,
+                                        const APInt &C, unsigned NoWrapKind);
+
   /// Return the lower value for this range.
   ///
   const APInt &getLower() const { return Lower; }
Index: lib/IR/ConstantRange.cpp
===================================================================
--- lib/IR/ConstantRange.cpp
+++ lib/IR/ConstantRange.cpp
@@ -21,7 +21,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/IR/Instruction.h"
 #include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Operator.h"
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -125,6 +127,37 @@
       .inverse();
 }
 
+ConstantRange ConstantRange::makeNoWrapRegion(Instruction::BinaryOps BinOp,
+                                              const APInt &C,
+                                              unsigned NoWrapKind) {
+  typedef OverflowingBinaryOperator OBO;
+
+  assert(BinOp >= Instruction::BinaryOpsBegin &&
+         BinOp < Instruction::BinaryOpsEnd && "Binary operators only!");
+
+  assert((NoWrapKind == OBO::NoSignedWrap ||
+          NoWrapKind == OBO::NoUnsignedWrap) && "NoWrapKind invalid!");
+
+  unsigned BitWidth = C.getBitWidth();
+  if (BinOp != Instruction::Add)
+    // Conservative answer: empty set
+    return ConstantRange(BitWidth, false);
+
+  if (C.isMinValue())
+    // Full set: nothing signed / unsigned wraps when added to 0.
+    return ConstantRange(BitWidth);
+
+  if (NoWrapKind == OBO::NoUnsignedWrap)
+    return ConstantRange(APInt::getNullValue(BitWidth), -C);
+
+  if (C.isStrictlyPositive())
+    return ConstantRange(APInt::getSignedMinValue(BitWidth),
+                         APInt::getSignedMinValue(BitWidth) - C);
+
+  return ConstantRange(APInt::getSignedMinValue(BitWidth) - C,
+                       APInt::getSignedMinValue(BitWidth));
+}
+
 /// isFullSet - Return true if this set contains all of the elements possible
 /// for this data-type
 bool ConstantRange::isFullSet() const {
Index: unittests/IR/ConstantRangeTest.cpp
===================================================================
--- unittests/IR/ConstantRangeTest.cpp
+++ unittests/IR/ConstantRangeTest.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/Operator.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
@@ -568,4 +569,38 @@
       ConstantRange(APInt(8, 4), APInt(8, -128)));
 }
 
+TEST(ConstantRange, MakeOverflowingRegion) {
+  const int IntMin4Bits = 8;
+  const int IntMax4Bits = 7;
+  typedef OverflowingBinaryOperator OBO;
+
+  for (int Const : {0, -1, -2, 1, 2, IntMin4Bits, IntMax4Bits}) {
+    APInt C(4, Const, true /* = isSigned */);
+
+    auto NUWRegion =
+      ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoUnsignedWrap);
+
+    EXPECT_FALSE(NUWRegion.isEmptySet());
+
+    auto NSWRegion =
+      ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoSignedWrap);
+
+    EXPECT_FALSE(NSWRegion.isEmptySet());
+
+    for (APInt I = NUWRegion.getLower(), E = NUWRegion.getUpper(); I != E;
+         ++I) {
+      bool Overflow = false;
+      I.uadd_ov(C, Overflow);
+      EXPECT_FALSE(Overflow);
+    }
+
+    for (APInt I = NSWRegion.getLower(), E = NSWRegion.getUpper(); I != E;
+         ++I) {
+      bool Overflow = false;
+      I.sadd_ov(C, Overflow);
+      EXPECT_FALSE(Overflow);
+    }
+  }
+}
+
 }  // anonymous namespace