Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -650,7 +650,8 @@
     } else if (match(Arg, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)),
                                    m_Value(A))) &&
                Pred == ICmpInst::ICMP_EQ &&
-               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
+               isValidAssumeForContext(I, Q.CxtI, Q.DT) &&
+               C->getZExtValue() < BitWidth) {
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
       // For those bits in RHS that are known, we can propagate them to known
@@ -663,7 +664,8 @@
     } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))),
                                    m_Value(A))) &&
                Pred == ICmpInst::ICMP_EQ &&
-               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
+               isValidAssumeForContext(I, Q.CxtI, Q.DT) &&
+               C->getZExtValue() < BitWidth) {
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
       // For those bits in RHS that are known, we can propagate them inverted
@@ -677,7 +679,8 @@
                      m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)),
                               m_Value(A))) &&
                Pred == ICmpInst::ICMP_EQ &&
-               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
+               isValidAssumeForContext(I, Q.CxtI, Q.DT) &&
+               C->getZExtValue() < BitWidth) {
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
       // For those bits in RHS that are known, we can propagate them to known
@@ -688,7 +691,8 @@
     } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))),
                                    m_Value(A))) &&
                Pred == ICmpInst::ICMP_EQ &&
-               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
+               isValidAssumeForContext(I, Q.CxtI, Q.DT) &&
+               C->getZExtValue() < BitWidth) {
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
       // For those bits in RHS that are known, we can propagate them inverted
Index: lib/Transforms/InstCombine/InstCombineVectorOps.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -611,7 +611,8 @@
   // until we hit something that isn't an insert of the splatted value.
   while (CurrIE) {
     ConstantInt *Idx = dyn_cast<ConstantInt>(CurrIE->getOperand(2));
-    if (!Idx || CurrIE->getOperand(1) != SplatVal)
+    if (!Idx || Idx->getSExtValue() >= NumElements ||
+        CurrIE->getOperand(1) != SplatVal)
       return nullptr;
 
     InsertElementInst *NextIE =
Index: test/Transforms/InstCombine/out-of-bounds-indexes.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/out-of-bounds-indexes.ll
@@ -0,0 +1,23 @@
+; RUN: opt < %s -instcombine -disable-output
+; Check that we don't crash on unreasonable constant indexes in various operations
+
+define void @test(<4 x double> %a, <4 x double> %b) {
+entry:
+  %sub.i = fsub ninf <4 x double> %a, %b
+  %I = insertelement <4 x double> %sub.i, double 0x7FEFFFFFFFFFFFFF, i64 4294967296
+  %B = lshr i8 127, 0
+  store i8 %B, i8* undef
+  store <4 x double> %I, <4 x double>* undef
+  ret void
+}
+
+define i32 @test2(i32 %a, i1 %x, i1 %y) {
+entry:
+  %and1 = and i32 %a, 3
+  %B = lshr i32 %and1, -2147483648
+  %cmp = icmp eq i32 %B, 1
+  tail call void @llvm.assume(i1 %cmp)
+  ret i32 %and1
+}
+
+declare void @llvm.assume(i1)