Index: include/llvm/Transforms/Utils/LoopUtils.h
===================================================================
--- include/llvm/Transforms/Utils/LoopUtils.h
+++ include/llvm/Transforms/Utils/LoopUtils.h
@@ -323,6 +323,25 @@
 BasicBlock *InsertPreheaderForLoop(Loop *L, DominatorTree *DT, LoopInfo *LI,
                                    bool PreserveLCSSA);
 
+/// \brief Ensures LCSSA form for instruction Inst in the scope of loop L.
+///
+/// For the given instruction in the loop which have uses outside of the loop,
+/// an LCSSA PHI node is inserted and the uses outside the loop are rewritten to
+/// use this node.
+///
+/// LoopInfo and DominatorTree are required and preserved.
+/// ExitBlocks is a vector containing exit blocks of the loop L.
+/// PredCache should be a valid PredIteratorCache object.
+///
+/// ExitBlocks and PredCache are used to avoid redundant recomputations for
+/// every call of this routine.
+///
+/// Returns true if any modifications are made.
+bool formLCSSAForInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
+                             LoopInfo &LI,
+                             const SmallVectorImpl<BasicBlock *> &ExitBlocks,
+                             PredIteratorCache &PredCache);
+
 /// \brief Put loop into LCSSA form.
 ///
 /// Looks at all instructions in the loop which have uses outside of the
Index: lib/Transforms/Utils/LCSSA.cpp
===================================================================
--- lib/Transforms/Utils/LCSSA.cpp
+++ lib/Transforms/Utils/LCSSA.cpp
@@ -60,9 +60,10 @@
 /// Given an instruction in the loop, check to see if it has any uses that are
 /// outside the current loop.  If so, insert LCSSA PHI nodes and rewrite the
 /// uses.
-static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
-                               const SmallVectorImpl<BasicBlock *> &ExitBlocks,
-                               PredIteratorCache &PredCache, LoopInfo *LI) {
+bool llvm::formLCSSAForInstruction(
+    Loop &L, Instruction &Inst, DominatorTree &DT, LoopInfo &LI,
+    const SmallVectorImpl<BasicBlock *> &ExitBlocks,
+    PredIteratorCache &PredCache) {
   SmallVector<Use *, 16> UsesToRewrite;
 
   // Tokens cannot be used in PHI nodes, so we skip over them.
@@ -145,7 +146,7 @@
     // have uses outside of L2. Remember all PHIs in such situation as to
     // revisit than later on. FIXME: Remove this if indirectbr support into
     // LoopSimplify gets improved.
-    if (auto *OtherLoop = LI->getLoopFor(ExitBB))
+    if (auto *OtherLoop = LI.getLoopFor(ExitBB))
       if (!L.contains(OtherLoop))
         PostProcessPHIs.push_back(PN);
   }
@@ -181,7 +182,7 @@
       continue;
 
     BasicBlock *PHIBB = I->getParent();
-    Loop *OtherLoop = LI->getLoopFor(PHIBB);
+    Loop *OtherLoop = LI.getLoopFor(PHIBB);
     SmallVector<BasicBlock *, 8> EBs;
     OtherLoop->getExitBlocks(EBs);
     if (EBs.empty())
@@ -190,7 +191,7 @@
     // Recurse and re-process each PHI instruction. FIXME: we should really
     // convert this entire thing to a worklist approach where we process a
     // vector of instructions...
-    processInstruction(*OtherLoop, *I, DT, EBs, PredCache, LI);
+    formLCSSAForInstruction(*OtherLoop, *I, DT, LI, EBs, PredCache);
   }
 
   // Remove PHI nodes that did not have any uses rewritten.
@@ -243,7 +244,7 @@
            !isa<PHINode>(I.user_back())))
         continue;
 
-      Changed |= processInstruction(L, I, DT, ExitBlocks, PredCache, LI);
+      Changed |= formLCSSAForInstruction(L, I, DT, *LI, ExitBlocks, PredCache);
     }
   }