diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -787,6 +787,8 @@
 unsigned DependenceInfo::mapDstLoop(const Loop *DstLoop) const {
   unsigned D = DstLoop->getLoopDepth();
   if (D > CommonLevels)
+    // This tries to make sure that we assign unique numbers to src and dst when
+    // the memory accesses reside in different loops that have the same depth.
     return D - CommonLevels + SrcLevels;
   else
     return D;
@@ -909,6 +911,13 @@
   }
   if (!isLoopInvariant(Step, LoopNest))
     return false;
+
+  // If the subscript loop does not contain (and is not equal to) the loop where
+  // the instruction resides, we may be dealing with an LCSSA situation that
+  // messes up our level numbering system.
+  if ((AddRec->getLoop() != LoopNest) && !AddRec->getLoop()->contains(LoopNest))
+    return false;
+
   if (IsSrc)
     Loops.set(mapSrcLoop(AddRec->getLoop()));
   else
diff --git a/llvm/test/Analysis/DependenceAnalysis/MismatchingNestLevels.ll b/llvm/test/Analysis/DependenceAnalysis/MismatchingNestLevels.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/MismatchingNestLevels.ll
@@ -0,0 +1,75 @@
+; RUN: opt < %s -disable-output "-passes=print<da>" -aa-pipeline=basic-aa 2>&1 | FileCheck %s
+
+; CHECK-LABEL: 'Dependence Analysis' for function 'test1':
+; CHECK: Src:  %src = load double, double* %arrayidx295, align 8 --> Dst:  %src = load double, double* %arrayidx295, align 8
+; CHECK-NEXT:    da analyze - consistent input [S 0]!
+; CHECK: Src:  %src = load double, double* %arrayidx295, align 8 --> Dst:  %1 = load double, double* %arrayidx98, align 8
+; CHECK-NEXT:    da analyze - input [*|<]!
+; CHECK: Src:  %1 = load double, double* %arrayidx98, align 8 --> Dst:  %1 = load double, double* %arrayidx98, align 8
+; CHECK-NEXT:    da analyze - input [*]!
+
+define dso_local void @test1([512 x double]* %temp) local_unnamed_addr {
+entry:
+  br label %for.cond1.preheader
+
+for.cond1.preheader:                              ; preds = %for.end63, %entry
+  br label %for.body272
+
+for.body272:                                      ; preds = %for.body272, %for.cond1.preheader
+  %r.1597 = phi i32 [ 1, %for.cond1.preheader ], [ %add277, %for.body272 ]
+  %idxprom274 = zext i32 %r.1597 to i64
+  %add277 = add nuw nsw i32 %r.1597, 1
+  %arrayidx295 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 %idxprom274, i64 510
+  %src = load double, double* %arrayidx295, align 8
+  br i1 undef, label %for.body272, label %for.body6
+
+for.body6:                                        ; preds = %for.body6, %for.body272
+  %c.2594 = phi i32 [ 1, %for.body272 ], [ %add27, %for.body6 ]
+  %add27 = add nuw nsw i32 %c.2594, 1
+  br i1 undef, label %for.body6, label %for.end63
+
+for.end63:                                        ; preds = %for.body6
+  %c.1.lcssa = phi i32 [ %add27, %for.body6 ]
+  %sub96 = add nsw i32 %c.1.lcssa, -1
+  %0 = zext i32 %sub96 to i64
+  %arrayidx98 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 0, i64 %0
+  %1 = load double, double* %arrayidx98, align 8
+  br label %for.cond1.preheader
+}
+
+; CHECK-LABEL: 'Dependence Analysis' for function 'test2':
+; CHECK: Src: %1 = load double, double* %arrayidx98, align 8 --> Dst:  %1 = load double, double* %arrayidx98, align 8
+; CHECK-NEXT:   da analyze - input [*]!
+; CHECK: Src: %1 = load double, double* %arrayidx98, align 8 --> Dst:  %2 = load double, double* %arrayidx295, align 8
+; CHECK-NEXT:   da analyze - input [*|<]!
+; CHECK: Src: %2 = load double, double* %arrayidx295, align 8 --> Dst:  %2 = load double, double* %arrayidx295, align 8
+; CHECK-NEXT:   da analyze - consistent input [S 0]!
+
+define dso_local void @test2([512 x double]* %temp) local_unnamed_addr #0 {
+entry:
+  br label %for.cond1.preheader
+
+for.cond1.preheader:                              ; preds = %for.body272, %entry
+  br label %for.body6
+
+for.body6:                                        ; preds = %for.body6, %for.cond1.preheader
+  %c.2594 = phi i32 [ 1, %for.cond1.preheader ], [ %add27, %for.body6 ]
+  %add27 = add nuw nsw i32 %c.2594, 1
+  br i1 undef, label %for.body6, label %for.end63
+
+for.end63:                                        ; preds = %for.body6
+  %c.1.lcssa = phi i32 [ %add27, %for.body6 ]
+  %sub96 = add nsw i32 %c.1.lcssa, -1
+  %0 = zext i32 %sub96 to i64
+  %arrayidx98 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 0, i64 %0
+  %1 = load double, double* %arrayidx98, align 8
+  br label %for.body272
+
+for.body272:                                      ; preds = %for.body272, %for.end63
+  %r.1597 = phi i32 [ 1, %for.end63 ], [ %add277, %for.body272 ]
+  %idxprom274 = zext i32 %r.1597 to i64
+  %add277 = add nuw nsw i32 %r.1597, 1
+  %arrayidx295 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 %idxprom274, i64 510
+  %2 = load double, double* %arrayidx295, align 8
+  br i1 undef, label %for.body272, label %for.cond1.preheader
+}