Index: lib/Transforms/Utils/FlattenCFG.cpp
===================================================================
--- lib/Transforms/Utils/FlattenCFG.cpp
+++ lib/Transforms/Utils/FlattenCFG.cpp
@@ -199,8 +199,34 @@
 
     if (Idx == -1)
       Idx = CIdx;
-    else if (CIdx != Idx)
-      return false;
+    else if (CIdx != Idx) {
+      bool EverChanged = false;
+      if (FirstCondBlock && LastCondBlock) {
+        // Do branch inversion.
+        BasicBlock *CurrBlock = LastCondBlock;
+
+        for (; CurrBlock != FirstCondBlock;
+             CurrBlock = CurrBlock->getSinglePredecessor()) {
+          if (!CurrBlock)
+            break;
+          BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
+          CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
+          if (!CI)
+            continue;
+
+          CmpInst::Predicate Predicate = CI->getPredicate();
+          // Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
+          if ((Predicate == CmpInst::ICMP_NE) ||
+              (Predicate == CmpInst::FCMP_ONE) ||
+              (Predicate == CmpInst::FCMP_UNE)) {
+            CI->setPredicate(ICmpInst::getInversePredicate(Predicate));
+            BI->swapSuccessors();
+            EverChanged = true;
+          }
+        }
+      }
+      return EverChanged;
+    }
 
     // PS is the successor which is not BB. Check successors to identify
     // the last conditional branch.
@@ -224,37 +250,6 @@
   BasicBlock *PS1 = TBB->getSuccessor(0);
   BasicBlock *PS2 = TBB->getSuccessor(1);
   BranchInst *PBI1 = dyn_cast<BranchInst>(PS1->getTerminator());
-  BranchInst *PBI2 = dyn_cast<BranchInst>(PS2->getTerminator());
-
-  // If PS1 does not jump into PS2, but PS2 jumps into PS1,
-  // attempt branch inversion.
-  if (!PBI1 || !PBI1->isUnconditional() ||
-      (PS1->getTerminator()->getSuccessor(0) != PS2)) {
-    // Check whether PS2 jumps into PS1.
-    if (!PBI2 || !PBI2->isUnconditional() ||
-        (PS2->getTerminator()->getSuccessor(0) != PS1))
-      return false;
-
-    // Do branch inversion.
-    BasicBlock *CurrBlock = LastCondBlock;
-    bool EverChanged = false;
-    for (;CurrBlock != FirstCondBlock;
-          CurrBlock = CurrBlock->getSinglePredecessor()) {
-      BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
-      CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
-      if (!CI)
-        continue;
-
-      CmpInst::Predicate Predicate = CI->getPredicate();
-      // Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
-      if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
-        CI->setPredicate(ICmpInst::getInversePredicate(Predicate));
-        BI->swapSuccessors();
-        EverChanged = true;
-      }
-    }
-    return EverChanged;
-  }
 
   // PS1 must have a conditional branch.
   if (!PBI1 || !PBI1->isUnconditional())
Index: test/Transforms/Util/flattencfg.ll
===================================================================
--- test/Transforms/Util/flattencfg.ll
+++ test/Transforms/Util/flattencfg.ll
@@ -24,3 +24,71 @@
 exit:                               ; preds = %entry, %b0, %b1
   ret void
 }
+
+; CHECK: and
+define void @test_fold_and(i32 %in_a) #0 {
+entry:
+  %cmp0 = icmp eq i32 %in_a, -1
+  br i1 %cmp0, label %b0, label %exit
+
+b0:                                ; preds = %entry
+  %cmp1 = icmp eq i32 %in_a, 0
+  br i1 %cmp1, label %b1, label %exit
+
+b1:                                       ; preds = %entry, %b0
+  br label %exit
+
+exit:                               ; preds = %entry, %b0, %b1
+  ret void
+}
+
+; CHECK: and
+define void @test_fold_and_reverse(i32 %in_a) #0 {
+entry:
+  %cmp0 = icmp eq i32 %in_a, -1
+  br i1 %cmp0, label %b0, label %exit
+
+b0:                                ; preds = %entry
+  %cmp1 = icmp ne i32 %in_a, 0
+  br i1 %cmp1, label %exit, label %b1
+
+b1:                                       ; preds = %entry, %b0
+  br label %exit
+
+exit:                               ; preds = %entry, %b0, %b1
+  ret void
+}
+
+; CHECK: or
+define void @test_fold_or(i32 %in_a) #0 {
+entry:
+  %cmp0 = icmp eq i32 %in_a, -1
+  br i1 %cmp0, label %b1, label %b0
+
+b0:                                ; preds = %entry
+  %cmp1 = icmp eq i32 %in_a, 0
+  br i1 %cmp1, label %b1, label %exit
+
+b1:                                       ; preds = %entry, %b0
+  br label %exit
+
+exit:                               ; preds = %entry, %b0, %b1
+  ret void
+}
+
+; CHECK: or
+define void @test_fold_or_reverse(i32 %in_a) #0 {
+entry:
+  %cmp0 = icmp eq i32 %in_a, -1
+  br i1 %cmp0, label %b1, label %b0
+
+b0:                                ; preds = %entry
+  %cmp1 = icmp ne i32 %in_a, 0
+  br i1 %cmp1, label %exit, label %b1
+
+b1:                                       ; preds = %entry, %b0
+  br label %exit
+
+exit:                               ; preds = %entry, %b0, %b1
+  ret void
+}