diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index e62daa63cd0..1ce0cbc1c4a 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -286,15 +286,28 @@ bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
     for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
          I != E; ++I)
       PromoteAliasSet(*I, ExitBlocks, InsertPts);
+
+    // Once we have promoted values across the loop body we have to recursively
+    // reform LCSSA as any nested loop may now have values defined within the
+    // loop used in the outer loop.
+    // FIXME: This is really heavy handed. It would be a bit better to use an
+    // SSAUpdater strategy during promotion that was LCSSA aware and reformed
+    // it as it went.
+    if (Changed)
+      formLCSSARecursively(*L, *DT, getAnalysisIfAvailable<ScalarEvolution>());
+
+  } else if (Changed) {
+    // If we have successfully changed the loop but not used SSAUpdater to
+    // re-write instructions throughout the loop body, re-form LCSSA just for
+    // this loop.
+    formLCSSA(*L, *DT, getAnalysisIfAvailable<ScalarEvolution>());
   }
 
-  // If we have successfully changed the loop, re-form LCSSA and also re-form
-  // LCSSA in the parent loop as hoisting or sinking may have broken it.
-  if (Changed) {
-    formLCSSA(*L, *DT, getAnalysisIfAvailable<ScalarEvolution>());
+  // Regardless of how we changed the loop, reform LCSSA on its parent as
+  // hoisting or sinking could have disrupted it.
+  if (Changed)
     if (Loop *ParentL = L->getParentLoop())
       formLCSSA(*ParentL, *DT, getAnalysisIfAvailable<ScalarEvolution>());
-  }
 
   // Clear out loops state information for the next iteration
   CurLoop = 0;
diff --git a/test/Transforms/LICM/lcssa-ssa-promoter.ll b/test/Transforms/LICM/lcssa-ssa-promoter.ll
new file mode 100644
index 00000000000..5df3ef12181
--- /dev/null
+++ b/test/Transforms/LICM/lcssa-ssa-promoter.ll
@@ -0,0 +1,76 @@
+; RUN: opt -S -basicaa -licm < %s | FileCheck %s
+;
+; Manually validate LCSSA form is preserved even after SSAUpdater is used to
+; promote things in the loop bodies.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x = common global i32 0, align 4
+@y = common global i32 0, align 4
+
+define void @PR18688() {
+; CHECK-LABEL: @PR18688(
+
+entry:
+  br i1 undef, label %return, label %outer.preheader
+
+outer.preheader:
+  br label %outer.header
+; CHECK: outer.preheader:
+; CHECK: br label %outer.header
+
+outer.header:
+  store i32 0, i32* @x, align 4
+  br i1 undef, label %outer.latch, label %inner.preheader
+; CHECK: outer.header:
+; CHECK-NEXT: br i1 undef, label %outer.latch, label %inner.preheader
+
+inner.preheader:
+  br label %inner.header
+; CHECK: inner.preheader:
+; CHECK-NEXT: br label %inner.header
+
+inner.header:
+  br i1 undef, label %inner.body.rhs, label %inner.latch
+; CHECK: inner.header:
+; CHECK-NEXT: %[[PHI0:[^,]+]] = phi i32 [ %{{[^,]+}}, %inner.latch ], [ 0, %inner.preheader ]
+; CHECK-NEXT: br i1 undef, label %inner.body.rhs, label %inner.latch
+
+inner.body.rhs:
+  store i32 0, i32* @x, align 4
+  br label %inner.latch
+; CHECK: inner.body.rhs:
+; CHECK-NEXT: br label %inner.latch
+
+inner.latch:
+  %y_val = load i32* @y, align 4
+  %icmp = icmp eq i32 %y_val, 0
+  br i1 %icmp, label %inner.exit, label %inner.header
+; CHECK: inner.latch:
+; CHECK-NEXT: %[[PHI1:[^,]+]] = phi i32 [ 0, %inner.body.rhs ], [ %[[PHI0]], %inner.header ]
+; CHECK-NEXT: br i1 %{{[^,]+}}, label %inner.exit, label %inner.header
+
+inner.exit:
+  br label %outer.latch
+; CHECK: inner.exit:
+; CHECK-NEXT: %[[INNER_LCSSA:[^,]+]] = phi i32 [ %[[PHI1]], %inner.latch ]
+; CHECK-NEXT: br label %outer.latch
+
+outer.latch:
+  br i1 undef, label %outer.exit, label %outer.header
+; CHECK: outer.latch:
+; CHECK-NEXT: %[[PHI2:[^,]+]] = phi i32 [ %[[INNER_LCSSA]], %inner.exit ], [ 0, %outer.header ]
+; CHECK-NEXT: br i1 {{.*}}, label %outer.exit, label %outer.header
+
+outer.exit:
+  br label %return
+; CHECK: outer.exit:
+; CHECK-NEXT: %[[OUTER_LCSSA:[^,]+]] = phi i32 [ %[[PHI2]], %outer.latch ]
+; CHECK-NEXT: store i32 %[[OUTER_LCSSA]]
+; CHECK-NEXT: br label %return
+
+return:
+  ret void
+}
+