Index: lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1820,6 +1820,13 @@
 
       auto *LI = dyn_cast<LoadInst>(IncValue);
       if (LI) {
+        // If there is a sequence of one or more load instructions, each loaded
+        // value is used as address of later load instruction, bitcast is
+        // necessary to change the value type, don't optimize it. For
+        // simplicity we give up if the load address comes from another load.
+        Value *Addr = LI->getOperand(0);
+        if (Addr == &CI || isa<LoadInst>(Addr))
+          return nullptr;
         if (LI->hasOneUse() && LI->isSimple())
           continue;
         // If a LoadInst has more than one use, changing the type of loaded
Index: test/Transforms/InstCombine/pr27703.ll
===================================================================
--- test/Transforms/InstCombine/pr27703.ll
+++ test/Transforms/InstCombine/pr27703.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define void @mem() {
+bb:
+  br label %bb6
+
+bb6:
+  %.0 = phi i8** [ undef, %bb ], [ %t2, %bb6 ]
+  %tmp = load i8*, i8** %.0, align 8
+  %bc = bitcast i8* %tmp to i8**
+  %t1 = load i8*, i8** %bc, align 8
+  %t2 = bitcast i8* %t1 to i8**
+  br label %bb6
+
+bb206:
+  ret void
+; CHECK: phi
+; CHECK: bitcast
+; CHECK: load
+}