Index: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
+++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
@@ -1411,9 +1411,16 @@
       continue;
     auto *OrigBB = cast<BasicBlock>(Entry.first);
     auto *ClonedBB = cast<BasicBlock>(Entry.second);
-    ClonedBBs.insert(ClonedBB);
-    CallerBFI->setBlockFreq(ClonedBB,
-                            CalleeBFI->getBlockFreq(OrigBB).getFrequency());
+    uint64_t Freq = CalleeBFI->getBlockFreq(OrigBB).getFrequency();
+    if (!ClonedBBs.insert(ClonedBB).second) {
+      // Multiple blocks in the callee might get mapped to one cloned block in
+      // the caller since we prune the callee as we clone it. When that happens,
+      // we want to use the maximum among the original blocks' frequencies.
+      uint64_t NewFreq = CallerBFI->getBlockFreq(ClonedBB).getFrequency();
+      if (NewFreq > Freq)
+        Freq = NewFreq;
+    }
+    CallerBFI->setBlockFreq(ClonedBB, Freq);
   }
   BasicBlock *EntryClone = cast<BasicBlock>(VMap.lookup(&CalleeEntryBlock));
   CallerBFI->setBlockFreqAndScale(
Index: llvm/trunk/test/Transforms/Inline/bfi-update.ll
===================================================================
--- llvm/trunk/test/Transforms/Inline/bfi-update.ll
+++ llvm/trunk/test/Transforms/Inline/bfi-update.ll
@@ -0,0 +1,93 @@
+; RUN: opt < %s -passes='require<profile-summary>,cgscc(inline)' -S -inline-threshold=50 -inline-cold-callsite-threshold=0 -hot-callsite-threshold=50 | FileCheck %s
+; This tests incremental updates to caller's BFI as a callee gets inlined.
+; In bottom-up inlining, first c->e inlining is considered and fails because
+; e's size exceeds the threshold of 50. Then a->c inlining is considered and it
+; succeeds. a's BFI is updated incrementally. As c's blocks get pruned, the 
+; block with label cond_false is removed and since the remanining code is
+; straight-line a single block gets cloned into a. This block should get the
+; maximum block frequency among the original blocks in c. If it gets the
+; frequency of the block with label cond_true in @c, its frequency will be
+; 1/10th of function a's entry block frequency, resulting in a callsite count of
+; 2 (since a's entry count is 20) which means that a->e callsite will be
+; considered cold and not inlined. 
+
+@data = external global i32
+; CHECK-LABEL: define i32 @a(
+define i32 @a(i32 %a1) !prof !21 {
+; CHECK-NOT: call i32 @c
+; CHECK-NOT: call i32 @e
+; CHECK: ret
+entry:
+  %cond = icmp sle i32 %a1, 1
+  %a2 = call i32 @c(i32 1)
+  br label %exit
+exit:
+  ret i32 %a2
+}
+
+declare void @ext();
+
+; CHECK: @c(i32 %c1) !prof [[COUNT1:![0-9]+]]
+define i32 @c(i32 %c1) !prof !23 {
+  call void @ext()
+  %cond = icmp sle i32 %c1, 1
+  br i1 %cond, label %cond_true, label %cond_false, !prof !25
+
+cond_false:
+  br label %exit
+
+cond_true:
+  %c11 = call i32 @e(i32 %c1)
+  br label %exit
+exit:
+  %c12 = phi i32 [ 0, %cond_false], [ %c11, %cond_true ]
+  ret i32 %c12
+}
+
+
+; CHECK: @e(i32 %c1) !prof [[COUNT2:![0-9]+]]
+define i32 @e(i32 %c1) !prof !24 {
+  call void @ext()
+  call void @ext()
+  %cond = icmp sle i32 %c1, 1
+  br i1 %cond, label %cond_true, label %cond_false
+
+cond_false:
+  call void @ext()
+  %c2 = load i32, i32* @data, align 4
+  %c3 = add i32 %c1, %c2
+  %c4 = mul i32 %c3, %c2
+  %c5 = add i32 %c4, %c2
+  %c6 = mul i32 %c5, %c2
+  %c7 = add i32 %c6, %c2
+  %c8 = mul i32 %c7, %c2
+  %c9 = add i32 %c8, %c2
+  %c10 = mul i32 %c9, %c2
+  ret i32 %c10
+
+cond_true:
+  ret i32 0
+}
+
+; CHECK: [[COUNT1]] = !{!"function_entry_count", i64 480}
+; CHECK: [[COUNT2]] = !{!"function_entry_count", i64 80}
+!21 = !{!"function_entry_count", i64 20}
+!23 = !{!"function_entry_count", i64 500}
+!24 = !{!"function_entry_count", i64 100}
+!25 = !{!"branch_weights", i32 1, i32 9}
+
+!llvm.module.flags = !{!1}
+!1 = !{i32 1, !"ProfileSummary", !2}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
+!3 = !{!"ProfileFormat", !"InstrProf"}
+!4 = !{!"TotalCount", i64 10000}
+!5 = !{!"MaxCount", i64 1000}
+!6 = !{!"MaxInternalCount", i64 1}
+!7 = !{!"MaxFunctionCount", i64 1000}
+!8 = !{!"NumCounts", i64 3}
+!9 = !{!"NumFunctions", i64 3}
+!10 = !{!"DetailedSummary", !11}
+!11 = !{!12, !13, !14}
+!12 = !{i32 10000, i64 1000, i32 1}
+!13 = !{i32 999000, i64 1000, i32 1}
+!14 = !{i32 999999, i64 5, i32 2}