Index: include/llvm/Analysis/AliasSetTracker.h
===================================================================
--- include/llvm/Analysis/AliasSetTracker.h
+++ include/llvm/Analysis/AliasSetTracker.h
@@ -69,10 +69,15 @@
       if (AAInfo == DenseMapInfo<AAMDNodes>::getEmptyKey())
         // We don't have a AAInfo yet. Set it to NewAAInfo.
         AAInfo = NewAAInfo;
-      else if (AAInfo != NewAAInfo)
-        // NewAAInfo conflicts with AAInfo.
-        AAInfo = DenseMapInfo<AAMDNodes>::getTombstoneKey();
-
+      else {
+        AAMDNodes Intersection(AAInfo.intersect(NewAAInfo));
+        if (!Intersection) {
+          // NewAAInfo conflicts with AAInfo.
+          AAInfo = DenseMapInfo<AAMDNodes>::getTombstoneKey();
+          return SizeChanged;
+        }
+        AAInfo = Intersection;
+      }
       return SizeChanged;
     }
 
Index: include/llvm/IR/Metadata.h
===================================================================
--- include/llvm/IR/Metadata.h
+++ include/llvm/IR/Metadata.h
@@ -660,6 +660,19 @@
 
   /// \brief The tag specifying the noalias scope.
   MDNode *NoAlias;
+
+  /// \brief Given two sets of AAMDNodes that apply to the same pointer,
+  /// give the best AAMDNodes that are compatible with both (i.e. a set of
+  /// nodes whose allowable aliasing conclusions are a subset of those
+  /// allowable by both of the inputs). However, for efficiency
+  /// reasons, do not create any new MDNodes.
+  AAMDNodes intersect(const AAMDNodes &Other) {
+    AAMDNodes Result;
+    Result.TBAA = Other.TBAA == TBAA ? TBAA : nullptr;
+    Result.Scope = Other.Scope == Scope ? Scope : nullptr;
+    Result.NoAlias = Other.NoAlias == NoAlias ? NoAlias : nullptr;
+    return Result;
+  }
 };
 
 // Specialize DenseMapInfo for AAMDNodes.
Index: test/Transforms/LICM/dropped-tbaa.ll
===================================================================
--- /dev/null
+++ test/Transforms/LICM/dropped-tbaa.ll
@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -scoped-noalias -tbaa -licm -S | FileCheck %s
+
+; This test case case is generated from the following C code with -fstrict-aliasing,
+; and after passing through -inline -mem2reg -loop-rotate -instcombine
+; void add(double *restrict data, int *restrict addend) {
+;    *data += *addend;
+; }
+;
+; void foo(double *data, int *addend) {
+;    for (int i = 0; i < 1000; ++i) {
+;        *data += *addend;
+;        add(data, addend);
+;    }
+; }
+; We want to make sure the load of addend gets hoisted, independent of the second load
+; load having different noalias metadata.
+
+define void @foo(double* %data, i32* %addend) #0 {
+; CHECK:       for.body.lr.ph:
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, i32* [[ADDEND:%.*]], align 4, !tbaa !1
+; CHECK-NEXT:    [[CONV:%.*]] = sitofp i32 [[TMP1]] to double
+; CHECK-NEXT:    [[TMP2:%.*]] = load i32, i32* [[ADDEND]], align 4, !tbaa !1, !alias.scope !5, !noalias !8
+; CHECK-NEXT:    [[CONV_I:%.*]] = sitofp i32 [[TMP2]] to double
+entry:
+  %i = alloca i32, align 4
+  %0 = bitcast i32* %i to i8*
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #2
+  store i32 0, i32* %i, align 4, !tbaa !1
+  br i1 true, label %for.body.lr.ph, label %for.cond.cleanup
+
+for.body.lr.ph:                                   ; preds = %entry
+  br label %for.body
+
+for.cond.for.cond.cleanup_crit_edge:              ; preds = %for.inc
+  br label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.for.cond.cleanup_crit_edge, %entry
+  %1 = bitcast i32* %i to i8*
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %1) #2
+  br label %for.end
+
+for.body:                                         ; preds = %for.body.lr.ph, %for.inc
+  %2 = load i32, i32* %addend, align 4, !tbaa !1
+  %conv = sitofp i32 %2 to double
+  %3 = load i32, i32* %i, align 4, !tbaa !1
+  %idxprom = sext i32 %3 to i64
+  %arrayidx = getelementptr inbounds double, double* %data, i64 %idxprom
+  %4 = load double, double* %arrayidx, align 8, !tbaa !5
+  %add = fadd double %4, %conv
+  store double %add, double* %arrayidx, align 8, !tbaa !5
+  %idxprom1 = sext i32 %3 to i64
+  %arrayidx2 = getelementptr inbounds double, double* %data, i64 %idxprom1
+  %5 = load i32, i32* %addend, align 4, !tbaa !1, !alias.scope !7, !noalias !10
+  %conv.i = sitofp i32 %5 to double
+  %6 = load double, double* %arrayidx2, align 8, !tbaa !5, !alias.scope !10, !noalias !7
+  %add.i = fadd double %6, %conv.i
+  store double %add.i, double* %arrayidx2, align 8, !tbaa !5, !alias.scope !10, !noalias !7
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body
+  %7 = load i32, i32* %i, align 4, !tbaa !1
+  %inc = add nsw i32 %7, 1
+  store i32 %inc, i32* %i, align 4, !tbaa !1
+  %cmp = icmp slt i32 %inc, 1000
+  br i1 %cmp, label %for.body, label %for.cond.for.cond.cleanup_crit_edge
+
+for.end:                                          ; preds = %for.cond.cleanup
+  ret void
+}
+
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #0
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #0
+
+attributes #0 = { argmemonly nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 5.0.0  (llvm/trunk 299971)"}
+!1 = !{!2, !2, i64 0}
+!2 = !{!"int", !3, i64 0}
+!3 = !{!"omnipotent char", !4, i64 0}
+!4 = !{!"Simple C/C++ TBAA"}
+!5 = !{!6, !6, i64 0}
+!6 = !{!"double", !3, i64 0}
+!7 = !{!8}
+!8 = distinct !{!8, !9, !"add: %addend"}
+!9 = distinct !{!9, !"add"}
+!10 = !{!11}
+!11 = distinct !{!11, !9, !"add: %data"}