Index: lib/Analysis/BranchProbabilityInfo.cpp
===================================================================
--- lib/Analysis/BranchProbabilityInfo.cpp
+++ lib/Analysis/BranchProbabilityInfo.cpp
@@ -322,6 +322,9 @@
       InEdges.push_back(I.getSuccessorIndex());
   }
 
+  if (BackEdges.empty() && ExitingEdges.empty())
+    return false;
+
   if (uint32_t numBackEdges = BackEdges.size()) {
     uint32_t backWeight = LBH_TAKEN_WEIGHT / numBackEdges;
     if (backWeight < NORMAL_WEIGHT)
Index: test/Analysis/BranchProbabilityInfo/loop.ll
===================================================================
--- test/Analysis/BranchProbabilityInfo/loop.ll
+++ test/Analysis/BranchProbabilityInfo/loop.ll
@@ -15,7 +15,7 @@
   %i.0 = phi i32 [ 0, %entry ], [ %inc3, %do.end ]
   call void @g1()
   br label %do.body1
-; CHECK: edge do.body -> do.body1 probability is 124 / 124 = 100%
+; CHECK: edge do.body -> do.body1 probability is 16 / 16 = 100%
 
 do.body1:
   %j.0 = phi i32 [ 0, %do.body ], [ %inc, %do.body1 ]
@@ -55,8 +55,8 @@
   %i.010 = phi i32 [ 0, %for.body.lr.ph ], [ %inc5, %for.end ]
   call void @g1()
   br i1 %cmp27, label %for.body3, label %for.end
-; CHECK: edge for.body -> for.body3 probability is 62 / 124 = 50%
-; CHECK: edge for.body -> for.end probability is 62 / 124 = 50%
+; CHECK: edge for.body -> for.body3 probability is 20 / 32 = 62.5%
+; CHECK: edge for.body -> for.end probability is 12 / 32 = 37.5%
 
 for.body3:
   %j.08 = phi i32 [ %inc, %for.body3 ], [ 0, %for.body ]
@@ -91,8 +91,8 @@
   %0 = load i32* %c, align 4
   %cmp = icmp slt i32 %0, 42
   br i1 %cmp, label %do.body1, label %if.end
-; CHECK: edge do.body -> do.body1 probability is 62 / 124 = 50%
-; CHECK: edge do.body -> if.end probability is 62 / 124 = 50%
+; CHECK: edge do.body -> do.body1 probability is 16 / 32 = 50%
+; CHECK: edge do.body -> if.end probability is 16 / 32 = 50%
 
 do.body1:
   %j.0 = phi i32 [ %inc, %do.body1 ], [ 0, %do.body ]
@@ -165,7 +165,7 @@
   %i.0 = phi i32 [ 0, %entry ], [ %inc4, %do.end ]
   call void @g1()
   br label %do.body1
-; CHECK: edge do.body -> do.body1 probability is 124 / 124 = 100%
+; CHECK: edge do.body -> do.body1 probability is 16 / 16 = 100%
 
 do.body1:
   %j.0 = phi i32 [ 0, %do.body ], [ %inc, %if.end ]
@@ -209,7 +209,7 @@
   %i.0 = phi i32 [ 0, %entry ], [ %inc4, %do.end ]
   call void @g1()
   br label %do.body1
-; CHECK: edge do.body -> do.body1 probability is 124 / 124 = 100%
+; CHECK: edge do.body -> do.body1 probability is 16 / 16 = 100%
 
 do.body1:
   %j.0 = phi i32 [ 0, %do.body ], [ %inc, %do.cond ]
@@ -261,14 +261,14 @@
   %0 = load i32* %c, align 4
   %cmp1 = icmp eq i32 %0, %i.011
   br i1 %cmp1, label %for.inc5, label %if.end
-; CHECK: edge for.body -> for.inc5 probability is 62 / 124 = 50%
-; CHECK: edge for.body -> if.end probability is 62 / 124 = 50%
+; CHECK: edge for.body -> for.inc5 probability is 16 / 32 = 50%
+; CHECK: edge for.body -> if.end probability is 16 / 32 = 50%
 
 if.end:
   call void @g1()
   br i1 %cmp38, label %for.body4, label %for.end
-; CHECK: edge if.end -> for.body4 probability is 62 / 124 = 50%
-; CHECK: edge if.end -> for.end probability is 62 / 124 = 50%
+; CHECK: edge if.end -> for.body4 probability is 20 / 32 = 62.5%
+; CHECK: edge if.end -> for.end probability is 12 / 32 = 37.5%
 
 for.body4:
   %j.09 = phi i32 [ %inc, %for.body4 ], [ 0, %if.end ]
@@ -282,7 +282,7 @@
 for.end:
   call void @g3()
   br label %for.inc5
-; CHECK: edge for.end -> for.inc5 probability is 124 / 124 = 100%
+; CHECK: edge for.end -> for.inc5 probability is 16 / 16 = 100%
 
 for.inc5:
   %inc6 = add nsw i32 %i.011, 1
@@ -314,35 +314,35 @@
   %i.019 = phi i32 [ 0, %for.body.lr.ph ], [ %inc14, %for.end ]
   call void @g1()
   br i1 %cmp216, label %for.body3, label %for.end
-; CHECK: edge for.body -> for.body3 probability is 62 / 124 = 50%
-; CHECK: edge for.body -> for.end probability is 62 / 124 = 50%
+; CHECK: edge for.body -> for.body3 probability is 20 / 32 = 62.5%
+; CHECK: edge for.body -> for.end probability is 12 / 32 = 37.5%
 
 for.body3:
   %j.017 = phi i32 [ 0, %for.body ], [ %inc, %for.inc ]
   %0 = load i32* %c, align 4
   %cmp4 = icmp eq i32 %0, %j.017
   br i1 %cmp4, label %for.inc, label %if.end
-; CHECK: edge for.body3 -> for.inc probability is 62 / 124 = 50%
-; CHECK: edge for.body3 -> if.end probability is 62 / 124 = 50%
+; CHECK: edge for.body3 -> for.inc probability is 16 / 32 = 50%
+; CHECK: edge for.body3 -> if.end probability is 16 / 32 = 50%
 
 if.end:
   %1 = load i32* %arrayidx5, align 4
   %cmp6 = icmp eq i32 %1, %j.017
   br i1 %cmp6, label %for.inc, label %if.end8
-; CHECK: edge if.end -> for.inc probability is 62 / 124 = 50%
-; CHECK: edge if.end -> if.end8 probability is 62 / 124 = 50%
+; CHECK: edge if.end -> for.inc probability is 16 / 32 = 50%
+; CHECK: edge if.end -> if.end8 probability is 16 / 32 = 50%
 
 if.end8:
   %2 = load i32* %arrayidx9, align 4
   %cmp10 = icmp eq i32 %2, %j.017
   br i1 %cmp10, label %for.inc, label %if.end12
-; CHECK: edge if.end8 -> for.inc probability is 62 / 124 = 50%
-; CHECK: edge if.end8 -> if.end12 probability is 62 / 124 = 50%
+; CHECK: edge if.end8 -> for.inc probability is 16 / 32 = 50%
+; CHECK: edge if.end8 -> if.end12 probability is 16 / 32 = 50%
 
 if.end12:
   call void @g2()
   br label %for.inc
-; CHECK: edge if.end12 -> for.inc probability is 124 / 124 = 100%
+; CHECK: edge if.end12 -> for.inc probability is 16 / 16 = 100%
 
 for.inc:
   %inc = add nsw i32 %j.017, 1
Index: test/Analysis/BranchProbabilityInfo/pr18705.ll
===================================================================
--- /dev/null
+++ test/Analysis/BranchProbabilityInfo/pr18705.ll
@@ -0,0 +1,58 @@
+; RUN: opt < %s -analyze -branch-prob | FileCheck %s
+
+; Since neither of while.body's out-edges is an exit or a back edge,
+; calcLoopBranchHeuristics should return early without setting the weights.
+; calcFloatingPointHeuristics, which is run later, sets the weights.
+;
+; CHECK: edge while.body -> if.then probability is 20 / 32 = 62.5%
+; CHECK: edge while.body -> if.else probability is 12 / 32 = 37.5%
+
+define void @foo1(i32 %n, i32* nocapture %b, i32* nocapture %c, i32* nocapture %d, float* nocapture readonly %f0, float* nocapture readonly %f1) {
+entry:
+  %tobool8 = icmp eq i32 %n, 0
+  br i1 %tobool8, label %while.end, label %while.body.lr.ph
+
+while.body.lr.ph:
+  %0 = sext i32 %n to i64
+  br label %while.body
+
+while.body:
+  %indvars.iv = phi i64 [ %0, %while.body.lr.ph ], [ %indvars.iv.next, %if.end ]
+  %b.addr.011 = phi i32* [ %b, %while.body.lr.ph ], [ %b.addr.1, %if.end ]
+  %d.addr.010 = phi i32* [ %d, %while.body.lr.ph ], [ %incdec.ptr4, %if.end ]
+  %c.addr.09 = phi i32* [ %c, %while.body.lr.ph ], [ %c.addr.1, %if.end ]
+  %indvars.iv.next = add nsw i64 %indvars.iv, -1
+  %arrayidx = getelementptr inbounds float* %f0, i64 %indvars.iv.next
+  %1 = load float* %arrayidx, align 4
+  %arrayidx2 = getelementptr inbounds float* %f1, i64 %indvars.iv.next
+  %2 = load float* %arrayidx2, align 4
+  %cmp = fcmp une float %1, %2
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  %incdec.ptr = getelementptr inbounds i32* %b.addr.011, i64 1
+  %3 = load i32* %b.addr.011, align 4
+  %add = add nsw i32 %3, 12
+  store i32 %add, i32* %b.addr.011, align 4
+  br label %if.end
+
+if.else:
+  %incdec.ptr3 = getelementptr inbounds i32* %c.addr.09, i64 1
+  %4 = load i32* %c.addr.09, align 4
+  %sub = add nsw i32 %4, -13
+  store i32 %sub, i32* %c.addr.09, align 4
+  br label %if.end
+
+if.end:
+  %c.addr.1 = phi i32* [ %c.addr.09, %if.then ], [ %incdec.ptr3, %if.else ]
+  %b.addr.1 = phi i32* [ %incdec.ptr, %if.then ], [ %b.addr.011, %if.else ]
+  %incdec.ptr4 = getelementptr inbounds i32* %d.addr.010, i64 1
+  store i32 14, i32* %d.addr.010, align 4
+  %5 = trunc i64 %indvars.iv.next to i32
+  %tobool = icmp eq i32 %5, 0
+  br i1 %tobool, label %while.end, label %while.body
+
+while.end:
+  ret void
+}
+
Index: test/CodeGen/ARM/ifcvt-branch-weight-bug.ll
===================================================================
--- test/CodeGen/ARM/ifcvt-branch-weight-bug.ll
+++ test/CodeGen/ARM/ifcvt-branch-weight-bug.ll
@@ -24,7 +24,7 @@
 ; CHECK: BB#1: derived from LLVM BB %for.body
 ; CHECK: Successors according to CFG: BB#2(130023362) BB#4(62)
 for.body:
-  br i1 undef, label %for.cond.backedge, label %lor.lhs.false.i
+  br i1 undef, label %for.cond.backedge, label %lor.lhs.false.i, !prof !1
 
 for.cond.backedge:
   %tobool = icmp eq %classL* undef, null
@@ -60,3 +60,4 @@
 declare void @_Z3fn1v()
 
 !0 = metadata !{metadata !"clang version 3.5"}
+!1 = metadata !{metadata !"branch_weights", i32 62, i32 62}