diff --git a/deps/Makefile b/deps/Makefile
index b278351f543ab4..b791e89cbe64a7 100644
--- a/deps/Makefile
+++ b/deps/Makefile
@@ -728,6 +728,7 @@ $(eval $(call LLVM_PATCH,llvm-3.8.0_winshlib))
 $(eval $(call LLVM_PATCH,llvm-3.8.0_threads))
 # fix replutil test on unix
 $(eval $(call LLVM_PATCH,llvm-D17165))
+$(eval $(call LLVM_PATCH,llvm-D18583))
 endif # LLVM_VER
 
 ifeq ($(LLVM_VER),3.7.1)
diff --git a/deps/llvm-D18583.patch b/deps/llvm-D18583.patch
new file mode 100644
index 00000000000000..4139bb33233d1e
--- /dev/null
+++ b/deps/llvm-D18583.patch
@@ -0,0 +1,99 @@
+From af289e04413504c3bdc252e08c3fe17bf7ea6dc8 Mon Sep 17 00:00:00 2001
+From: Peter Collingbourne <peter@pcc.me.uk>
+Date: Wed, 30 Mar 2016 22:05:13 +0000
+Subject: [PATCH] Cloning: Reduce complexity of debug info cloning and fix
+ correctness issue.
+
+Commit r260791 contained an error in that it would introduce a cross-module
+reference in the old module. It also introduced O(N^2) complexity in the
+module cloner by requiring the entire module to be visited for each function.
+Fix both of these problems by avoiding use of the CloneDebugInfoMetadata
+function (which is only designed to do intra-module cloning) and cloning
+function-attached metadata in the same way that we clone all other metadata.
+
+Differential Revision: http://reviews.llvm.org/D18583
+
+git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264935 91177308-0d34-0410-b5e6-96231b3b80d8
+---
+ include/llvm/Transforms/Utils/Cloning.h |  5 -----
+ lib/Transforms/Utils/CloneFunction.cpp  | 13 +++++++++++--
+ lib/Transforms/Utils/CloneModule.cpp    |  1 -
+ unittests/Transforms/Utils/Cloning.cpp  |  6 ++++++
+ 4 files changed, 17 insertions(+), 8 deletions(-)
+
+diff --git a/include/llvm/Transforms/Utils/Cloning.h b/include/llvm/Transforms/Utils/Cloning.h
+index 0bae2bd..4f006f2 100644
+--- a/include/llvm/Transforms/Utils/Cloning.h
++++ b/include/llvm/Transforms/Utils/Cloning.h
+@@ -130,11 +130,6 @@ Function *CloneFunction(const Function *F, ValueToValueMapTy &VMap,
+                         bool ModuleLevelChanges,
+                         ClonedCodeInfo *CodeInfo = nullptr);
+ 
+-/// Clone the module-level debug info associated with OldFunc. The cloned data
+-/// will point to NewFunc instead.
+-void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
+-                            ValueToValueMapTy &VMap);
+-
+ /// Clone OldFunc into NewFunc, transforming the old arguments into references
+ /// to VMap values.  Note that if NewFunc already has basic blocks, the ones
+ /// cloned into it will be added to the end of the function.  This function
+diff --git a/lib/Transforms/Utils/CloneFunction.cpp b/lib/Transforms/Utils/CloneFunction.cpp
+index 05b0a17..8e1715a 100644
+--- a/lib/Transforms/Utils/CloneFunction.cpp
++++ b/lib/Transforms/Utils/CloneFunction.cpp
+@@ -119,6 +119,15 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
+           .addAttributes(NewFunc->getContext(), AttributeSet::FunctionIndex,
+                          OldAttrs.getFnAttributes()));
+ 
++  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
++  OldFunc->getAllMetadata(MDs);
++  for (auto MD : MDs)
++    NewFunc->setMetadata(
++        MD.first,
++        MapMetadata(MD.second, VMap,
++                    ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
++                    TypeMapper, Materializer));
++
+   // Loop over all of the basic blocks in the function, cloning them as
+   // appropriate.  Note that we save BE this way in order to handle cloning of
+   // recursive functions into themselves.
+@@ -187,8 +196,8 @@ static void AddOperand(DICompileUnit *CU, DISubprogramArray SPs,
+ 
+ // Clone the module-level debug info associated with OldFunc. The cloned data
+ // will point to NewFunc instead.
+-void llvm::CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
+-                                  ValueToValueMapTy &VMap) {
++static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
++                                   ValueToValueMapTy &VMap) {
+   DebugInfoFinder Finder;
+   Finder.processModule(*OldFunc->getParent());
+ 
+diff --git a/lib/Transforms/Utils/CloneModule.cpp b/lib/Transforms/Utils/CloneModule.cpp
+index 494e275..929f51b 100644
+--- a/lib/Transforms/Utils/CloneModule.cpp
++++ b/lib/Transforms/Utils/CloneModule.cpp
+@@ -138,7 +138,6 @@ std::unique_ptr<Module> llvm::CloneModule(
+         VMap[&*J] = &*DestI++;
+       }
+ 
+-      CloneDebugInfoMetadata(F, &*I, VMap);
+       SmallVector<ReturnInst*, 8> Returns;  // Ignore returns cloned.
+       CloneFunctionInto(F, &*I, VMap, /*ModuleLevelChanges=*/true, Returns);
+     }
+diff --git a/unittests/Transforms/Utils/Cloning.cpp b/unittests/Transforms/Utils/Cloning.cpp
+index b761e4e..f06a20f 100644
+--- a/unittests/Transforms/Utils/Cloning.cpp
++++ b/unittests/Transforms/Utils/Cloning.cpp
+@@ -464,6 +464,12 @@ TEST_F(CloneModule, Verify) {
+   EXPECT_FALSE(verifyModule(*NewM));
+ }
+ 
++TEST_F(CloneModule, OldModuleUnchanged) {
++  DebugInfoFinder Finder;
++  Finder.processModule(*OldM);
++  EXPECT_EQ(1U, Finder.subprogram_count());
++}
++
+ TEST_F(CloneModule, Subprogram) {
+   Function *NewF = NewM->getFunction("f");
+   DISubprogram *SP = NewF->getSubprogram();