Index: lib/Transforms/Scalar/Reassociate.cpp
===================================================================
--- lib/Transforms/Scalar/Reassociate.cpp
+++ lib/Transforms/Scalar/Reassociate.cpp
@@ -2097,6 +2097,20 @@
   ReassociateExpression(BO);
 }
 
+static bool canDropDebugLoc(Instruction *I) {
+  if (CallInst *CI = dyn_cast<CallInst>(I)) {
+    CallSite CS = CallSite(CI);
+    // Inlinable callsites of debug-info-bearing functions in
+    // debug-info-bearing functions must have debug locations
+    // attached to them. See rationale in the IR verifier.
+    if (CI->getFunction()->getSubprogram() && CS.getCalledFunction() &&
+        CS.getCalledFunction()->getSubprogram())
+      return false;
+  }
+
+  return true;
+}
+
 void ReassociatePass::ReassociateExpression(BinaryOperator *I) {
   // First, walk the expression tree, linearizing the tree, collecting the
   // operand information.
@@ -2131,7 +2145,8 @@
     DEBUG(dbgs() << "Reassoc to scalar: " << *V << '\n');
     I->replaceAllUsesWith(V);
     if (Instruction *VI = dyn_cast<Instruction>(V))
-      VI->setDebugLoc(I->getDebugLoc());
+      if (I->getDebugLoc() || canDropDebugLoc(VI))
+        VI->setDebugLoc(I->getDebugLoc());
     RedoInsts.insert(I);
     ++NumAnnihil;
     return;
Index: test/Transforms/Reassociate/keep-inlinable-fn-dbgloc.ll
===================================================================
--- /dev/null
+++ test/Transforms/Reassociate/keep-inlinable-fn-dbgloc.ll
@@ -0,0 +1,32 @@
+;RUN: opt -S -reassociate -disable-output < %s
+
+; Inlinable callsites of debug-info-bearing functions in
+; debug-info-bearing functions must have debug locations
+; attached to them. Therefore, do not drop debug locations for
+; such instructions when reassociating expressions.
+;
+; This would trigger an "inlinable function call in a function with "
+; "debug info must have a !dbg location" error in the verifier otherwise.
+
+define i16 @fn1() !dbg !3 {
+  ret i16 undef
+}
+
+define void @fn2() !dbg !6 {
+  %inlinable_call = call i16 @fn1(), !dbg !7
+  %dbgless_instruction = or i16 %inlinable_call, 0
+  store i16 %dbgless_instruction, i16* undef, align 1
+  unreachable
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly)
+!1 = !DIFile(filename: "foo.c", directory: "/")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = distinct !DISubprogram(name: "fn1", scope: !1, file: !1, line: 2, type: !4, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: true, unit: !0)
+!4 = !DISubroutineType(types: !5)
+!5 = !{}
+!6 = distinct !DISubprogram(name: "fn2", scope: !1, file: !1, line: 3, type: !4, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0)
+!7 = !DILocation(line: 7, column: 10, scope: !6)