diff --git a/include/llvm/IR/Instruction.h b/include/llvm/IR/Instruction.h
index 5721d8f2f3f..0a245483ff7 100644
--- a/include/llvm/IR/Instruction.h
+++ b/include/llvm/IR/Instruction.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_IR_INSTRUCTION_H
 #define LLVM_IR_INSTRUCTION_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/ilist_node.h"
 #include "llvm/IR/User.h"
 #include "llvm/Support/DebugLoc.h"
@@ -171,6 +172,21 @@ public:
   void setMetadata(unsigned KindID, MDNode *Node);
   void setMetadata(StringRef Kind, MDNode *Node);
 
+  /// \brief Drop unknown metadata.
+  /// Passes are required to drop metadata they don't understand. This is a
+  /// convenience method for passes to do so.
+  void dropUnknownMetadata(ArrayRef<unsigned> KnownIDs);
+  void dropUnknownMetadata() {
+    return dropUnknownMetadata(ArrayRef<unsigned>());
+  }
+  void dropUnknownMetadata(unsigned ID1) {
+    return dropUnknownMetadata(makeArrayRef(ID1));
+  }
+  void dropUnknownMetadata(unsigned ID1, unsigned ID2) {
+    unsigned IDs[] = {ID1, ID2};
+    return dropUnknownMetadata(IDs);
+  }
+
   /// setDebugLoc - Set the debug location information for this instruction.
   void setDebugLoc(const DebugLoc &Loc) { DbgLoc = Loc; }
 
diff --git a/lib/IR/Metadata.cpp b/lib/IR/Metadata.cpp
index a32d25c92ae..ad943de88cc 100644
--- a/lib/IR/Metadata.cpp
+++ b/lib/IR/Metadata.cpp
@@ -16,6 +16,7 @@
 #include "SymbolTableListTraitsImpl.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/IR/Instruction.h"
@@ -583,6 +584,50 @@ MDNode *Instruction::getMetadataImpl(StringRef Kind) const {
   return getMetadataImpl(getContext().getMDKindID(Kind));
 }
 
+void Instruction::dropUnknownMetadata(ArrayRef<unsigned> KnownIDs) {
+  SmallSet<unsigned, 5> KnownSet;
+  KnownSet.insert(KnownIDs.begin(), KnownIDs.end());
+
+  // Drop debug if needed
+  if (KnownSet.erase(LLVMContext::MD_dbg))
+    DbgLoc = DebugLoc();
+
+  if (!hasMetadataHashEntry())
+    return; // Nothing to remove!
+
+  DenseMap<const Instruction *, LLVMContextImpl::MDMapTy> &MetadataStore =
+      getContext().pImpl->MetadataStore;
+
+  if (KnownSet.empty()) {
+    // Just drop our entry at the store.
+    MetadataStore.erase(this);
+    setHasMetadataHashEntry(false);
+    return;
+  }
+
+  LLVMContextImpl::MDMapTy &Info = MetadataStore[this];
+  unsigned I;
+  unsigned E;
+  // Walk the array and drop any metadata we don't know.
+  for (I = 0, E = Info.size(); I != E;) {
+    if (KnownSet.count(Info[I].first)) {
+      ++I;
+      continue;
+    }
+
+    Info[I] = Info.back();
+    Info.pop_back();
+    --E;
+  }
+  assert(E == Info.size());
+
+  if (E == 0) {
+    // Drop our entry at the store.
+    MetadataStore.erase(this);
+    setHasMetadataHashEntry(false);
+  }
+}
+
 /// setMetadata - Set the metadata of of the specified kind to the specified
 /// node.  This updates/replaces metadata if already present, or removes it if
 /// Node is null.
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 0401b9a7f7d..effc08edaa3 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2154,6 +2154,14 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
     Instruction *NewBonus = 0;
     if (BonusInst) {
       NewBonus = BonusInst->clone();
+
+      // If we moved a load, we cannot any longer claim any knowledge about
+      // its potential value. The previous information might have been valid
+      // only given the branch precondition.
+      // For an analogous reason, we must also drop all the metadata whose
+      // semantics we don't understand.
+      NewBonus->dropUnknownMetadata(LLVMContext::MD_dbg);
+
       PredBlock->getInstList().insert(PBI, NewBonus);
       NewBonus->takeName(BonusInst);
       BonusInst->setName(BonusInst->getName()+".old");
diff --git a/test/Transforms/SimplifyCFG/basictest.ll b/test/Transforms/SimplifyCFG/basictest.ll
index 9c4edd68b80..d6958a9c111 100644
--- a/test/Transforms/SimplifyCFG/basictest.ll
+++ b/test/Transforms/SimplifyCFG/basictest.ll
@@ -41,3 +41,33 @@ return:                                           ; preds = %entry
 ; CHECK-LABEL: @test5(
 ; CHECK-NEXT: ret void
 }
+
+
+; PR14893
+define i8 @test6f() {
+; CHECK-LABEL: @test6f
+; CHECK: alloca i8, align 1
+; CHECK-NEXT: call i8 @test6g
+; CHECK-NEXT: icmp eq i8 %tmp, 0
+; CHECK-NEXT: load i8* %r, align 1{{$}}
+
+bb0:
+  %r = alloca i8, align 1
+  %tmp = call i8 @test6g(i8* %r)
+  %tmp1 = icmp eq i8 %tmp, 0
+  br i1 %tmp1, label %bb2, label %bb1
+bb1:
+  %tmp3 = load i8* %r, align 1, !range !2, !tbaa !1
+  %tmp4 = icmp eq i8 %tmp3, 1
+  br i1 %tmp4, label %bb2, label %bb3
+bb2:
+  br label %bb3
+bb3:
+  %tmp6 = phi i8 [ 0, %bb2 ], [ 1, %bb1 ]
+  ret i8 %tmp6
+}
+declare i8 @test6g(i8*)
+
+!0 = metadata !{metadata !1, metadata !1, i64 0}
+!1 = metadata !{metadata !"foo"}
+!2 = metadata !{i8 0, i8 2}