diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 0e8529a4b07..c0009cb9899 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -911,7 +911,6 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
                             SmallVectorImpl<NonLocalDepResult> &Result,
                             DenseMap<BasicBlock*, Value*> &Visited,
                             bool SkipFirstBlock) {
-
   // Look up the cached info for Pointer.
   ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
 
@@ -999,8 +998,17 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
     for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
          I != E; ++I) {
       Visited.insert(std::make_pair(I->getBB(), Addr));
-      if (!I->getResult().isNonLocal() && DT->isReachableFromEntry(I->getBB()))
+      if (I->getResult().isNonLocal()) {
+        continue;
+      }
+
+      if (!DT) {
+        Result.push_back(NonLocalDepResult(I->getBB(),
+                                           MemDepResult::getUnknown(),
+                                           Addr));
+      } else if (DT->isReachableFromEntry(I->getBB())) {
         Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
+      }
     }
     ++NumCacheCompleteNonLocalPtr;
     return false;
@@ -1045,9 +1053,16 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
                                                  NumSortedEntries);
 
       // If we got a Def or Clobber, add this to the list of results.
-      if (!Dep.isNonLocal() && DT->isReachableFromEntry(BB)) {
-        Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
-        continue;
+      if (!Dep.isNonLocal()) {
+        if (!DT) {
+          Result.push_back(NonLocalDepResult(BB,
+                                             MemDepResult::getUnknown(),
+                                             Pointer.getAddr()));
+          continue;
+        } else if (DT->isReachableFromEntry(BB)) {
+          Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
+          continue;
+        }
       }
     }
 
diff --git a/test/Analysis/MemoryDependenceAnalysis/lit.local.cfg b/test/Analysis/MemoryDependenceAnalysis/lit.local.cfg
new file mode 100644
index 00000000000..c6106e4746f
--- /dev/null
+++ b/test/Analysis/MemoryDependenceAnalysis/lit.local.cfg
@@ -0,0 +1 @@
+config.suffixes = ['.ll']
diff --git a/test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll b/test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll
new file mode 100644
index 00000000000..3c957708d70
--- /dev/null
+++ b/test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll
@@ -0,0 +1,19 @@
+; RUN: opt -memdep -gvn < %s
+
+define void @__memdep_requires_dominator_tree(i32* nocapture %bufUInt, i32* nocapture %pattern) nounwind {
+entry:
+  br label %for.body
+
+for.exit:                                         ; preds = %for.body
+  ret void
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.01 = phi i32 [ 0, %entry ], [ %tmp8.7, %for.body ]
+  %arrayidx = getelementptr i32* %bufUInt, i32 %i.01
+  %arrayidx5 = getelementptr i32* %pattern, i32 %i.01
+  %tmp6 = load i32* %arrayidx5, align 4
+  store i32 %tmp6, i32* %arrayidx, align 4
+  %tmp8.7 = add i32 %i.01, 8
+  %cmp.7 = icmp ult i32 %tmp8.7, 1024
+  br i1 %cmp.7, label %for.body, label %for.exit
+}
diff --git a/test/Transforms/GVN/unreachable_block_infinite_loop.ll b/test/Transforms/GVN/unreachable_block_infinite_loop.ll
new file mode 100644
index 00000000000..fe335ced5c3
--- /dev/null
+++ b/test/Transforms/GVN/unreachable_block_infinite_loop.ll
@@ -0,0 +1,14 @@
+; RUN: opt -memdep -gvn -disable-output
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0"
+
+define i32 @test2() nounwind ssp {
+entry:
+    ret i32 0
+
+unreachable_block:
+    %a = add i32 %a, 1
+    ret i32 %a
+}
+