Index: lib/Transforms/Utils/SimplifyIndVar.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyIndVar.cpp
+++ lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -25,10 +25,12 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
+using namespace llvm::PatternMatch;
 
 #define DEBUG_TYPE "indvars"
 
@@ -522,9 +524,30 @@
 }
 
 /// Annotate BO with nsw / nuw if it provably does not signed-overflow /
-/// unsigned-overflow.  Returns true if anything changed, false otherwise.
+/// unsigned-overflow.  Also check for shifts that can be marked as exact.
+/// Returns true if anything changed, false otherwise.
 bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
                                                     Value *IVOperand) {
+  // match (X << IVOperand) >> C, marking the Shr as exact using the
+  // information from the IV's range
+  if (BO->getOpcode() == Instruction::Shl) {
+    bool Changed = false;
+    ConstantRange IVRange = SE->getUnsignedRange(SE->getSCEV(IVOperand));
+    for (auto *U : BO->users()) {
+      const APInt *C;
+      if (match(U,
+                m_AShr(m_Shl(m_Value(), m_Specific(IVOperand)), m_APInt(C))) ||
+          match(U,
+                m_LShr(m_Shl(m_Value(), m_Specific(IVOperand)), m_APInt(C)))) {
+        BinaryOperator *Shr = cast<BinaryOperator>(U);
+        if (!Shr->isExact() && IVRange.getUnsignedMin().uge(*C)) {
+          Shr->setIsExact(true);
+          Changed = true;
+        }
+      }
+    }
+    return Changed;
+  }
 
   // Fastpath: we don't have any work to do if `BO` is `nuw` and `nsw`.
   if (BO->hasNoUnsignedWrap() && BO->hasNoSignedWrap())
Index: test/Transforms/IndVarSimplify/strengthen-overflow.ll
===================================================================
--- test/Transforms/IndVarSimplify/strengthen-overflow.ll
+++ test/Transforms/IndVarSimplify/strengthen-overflow.ll
@@ -104,5 +104,89 @@
   ret i32 42
 }
 
+define hidden void @test.shl.exact.equal() {
+; CHECK-LABEL: @test.shl.exact.equal
+entry:
+  br label %for.body
+
+for.body:
+; CHECK-LABEL: for.body
+  %k.021 = phi i32 [ 1, %entry ], [ %inc, %for.body ]
+  %shl = shl i32 1, %k.021
+  %shr1 = ashr i32 %shl, 1
+; CHECK: %shr1 = ashr exact i32 %shl, 1
+  %shr2 = lshr i32 %shl, 1
+; CHECK: %shr2 = lshr exact i32 %shl, 1
+  %inc = add nuw nsw i32 %k.021, 1
+  %exitcond = icmp eq i32 %inc, 9
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+define hidden void @test.shl.exact.greater() {
+; CHECK-LABEL: @test.shl.exact.greater
+entry:
+  br label %for.body
+
+for.body:
+; CHECK-LABEL: for.body
+  %k.021 = phi i32 [ 3, %entry ], [ %inc, %for.body ]
+  %shl = shl i32 1, %k.021
+  %shr1 = ashr i32 %shl, 2
+; CHECK: %shr1 = ashr exact i32 %shl, 2
+  %shr2 = lshr i32 %shl, 2
+; CHECK: %shr2 = lshr exact i32 %shl, 2
+  %inc = add nuw nsw i32 %k.021, 1
+  %exitcond = icmp eq i32 %inc, 9
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+define hidden void @test.shl.exact.unbound(i32 %arg) {
+; CHECK-LABEL: @test.shl.exact.unbound
+entry:
+  br label %for.body
+
+for.body:
+; CHECK-LABEL: for.body
+  %k.021 = phi i32 [ 2, %entry ], [ %inc, %for.body ]
+  %shl = shl i32 1, %k.021
+  %shr1 = ashr i32 %shl, 2
+; CHECK: %shr1 = ashr exact i32 %shl, 2
+  %shr2 = lshr i32 %shl, 2
+; CHECK: %shr2 = lshr exact i32 %shl, 2
+  %inc = add nuw nsw i32 %k.021, 1
+  %exitcond = icmp eq i32 %inc, %arg
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+define hidden void @test.shl.nonexact() {
+; CHECK-LABEL: @test.shl.nonexact
+entry:
+  br label %for.body
+
+for.body:
+; CHECK-LABEL: for.body
+  %k.021 = phi i32 [ 2, %entry ], [ %inc, %for.body ]
+  %shl = shl i32 1, %k.021
+  %shr1 = ashr i32 %shl, 3
+; CHECK: %shr1 = ashr i32 %shl, 3
+  %shr2 = lshr i32 %shl, 3
+; CHECK: %shr2 = lshr i32 %shl, 3
+  %inc = add nuw nsw i32 %k.021, 1
+  %exitcond = icmp eq i32 %inc, 9
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
 !0 = !{i32 0, i32 2}
 !1 = !{i32 0, i32 42}