Index: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1375,7 +1375,7 @@
   // As the parent basic block terminator is a branch instruction which is
   // removed at the end of the current transformation, use its previous
   // non-debug instruction, as the reference insertion point, which will
-  // provide the debug location for the instruction being hoisted. For BBs
+  // provide the debug location for generated select instructions. For BBs
   // with only debug instructions, use an empty debug location.
   Instruction *InsertPt =
       BIParent->getTerminator()->getPrevNonDebugInstruction();
@@ -1389,15 +1389,16 @@
     NT->takeName(I1);
   }
 
-  // The instruction NT being hoisted, is the terminator for the true branch,
-  // with debug location (DILocation) within that branch. We can't retain
-  // its original debug location value, otherwise 'select' instructions that
-  // are created from any PHI nodes, will take its debug location, giving
-  // the impression that those 'select' instructions are in the true branch,
-  // causing incorrect stepping, affecting the debug experience.
-  NT->setDebugLoc(InsertPt ? InsertPt->getDebugLoc() : DebugLoc());
+  // Ensure terminator gets a debug location, even an unknown one, in case
+  // it involves inlinable calls.
+  NT->applyMergedLocation(I1->getDebugLoc(), I2->getDebugLoc());
 
   IRBuilder<NoFolder> Builder(NT);
+  // If an earlier instruction in this BB had a location, adopt it, otherwise
+  // clear debug locations.
+  Builder.SetCurrentDebugLocation(InsertPt ? InsertPt->getDebugLoc()
+                                           : DebugLoc());
+
   // Hoisting one of the terminators from our successor is a great thing.
   // Unfortunately, the successors of the if/else blocks may have PHI nodes in
   // them.  If they do, all PHI entries for BB1/BB2 must agree for all PHI
Index: llvm/trunk/test/Transforms/SimplifyCFG/pr39807.ll
===================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/pr39807.ll
+++ llvm/trunk/test/Transforms/SimplifyCFG/pr39807.ll
@@ -0,0 +1,43 @@
+; RUN: opt -S -simplifycfg < %s | FileCheck %s
+
+declare void @personality()
+
+define void @test(i1 %b) personality void()* @personality !dbg !1 {
+; CHECK:      invoke void @inlinable()
+; CHECK-NEXT:    to label %success unwind label %failure, !dbg ![[DBGLOC:[0-9]+]]
+    br i1 %b, label %if, label %else
+
+if:
+    invoke void @inlinable()
+        to label %success unwind label %failure, !dbg !2
+
+else:
+    invoke void @inlinable()
+        to label %success unwind label %failure, !dbg !8
+
+success:
+    ret void
+
+failure:
+    landingpad {}
+        cleanup
+    ret void
+}
+
+define internal void @inlinable() !dbg !7 {
+    ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!4, !5, !6}
+
+; CHECK: ![[DBGLOC]] = !DILocation(line: 0
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, runtimeVersion: 0, file: !3)
+!1 = distinct !DISubprogram(name: "test", unit: !0)
+!2 = !DILocation(line: 2, scope: !1)
+!3 = !DIFile(filename: "foo", directory: ".")
+!4 = !{i32 2, !"Dwarf Version", i32 4}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = !{i32 1, !"wchar_size", i32 4}
+!7 = distinct !DISubprogram(name: "inlinable", unit: !0)
+!8 = !DILocation(line: 3, scope: !1)