diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -405,6 +405,12 @@
         continue;
       while (ProcessBlock(&BB)) // Thread all of the branches we can over BB.
         Changed = true;
+
+      // Jump threading may have introduced redundant debug values into BB
+      // which should be removed.
+      if (Changed)
+        RemoveRedundantDbgInstrs(&BB);
+
       // Stop processing BB if it's the entry or is now deleted. The following
       // routines attempt to eliminate BB and locating a suitable replacement
       // for the entry is non-trivial.
@@ -427,17 +433,21 @@
       // ProcessBlock doesn't thread BBs with unconditional TIs. However, if BB
       // is "almost empty", we attempt to merge BB with its sole successor.
       auto *BI = dyn_cast<BranchInst>(BB.getTerminator());
-      if (BI && BI->isUnconditional() &&
-          // The terminator must be the only non-phi instruction in BB.
-          BB.getFirstNonPHIOrDbg()->isTerminator() &&
-          // Don't alter Loop headers and latches to ensure another pass can
-          // detect and transform nested loops later.
-          !LoopHeaders.count(&BB) && !LoopHeaders.count(BI->getSuccessor(0)) &&
-          TryToSimplifyUncondBranchFromEmptyBlock(&BB, DTU)) {
-        // BB is valid for cleanup here because we passed in DTU. F remains
-        // BB's parent until a DTU->getDomTree() event.
-        LVI->eraseBlock(&BB);
-        Changed = true;
+      if (BI && BI->isUnconditional()) {
+        BasicBlock *Succ = BI->getSuccessor(0);
+        if (
+            // The terminator must be the only non-phi instruction in BB.
+            BB.getFirstNonPHIOrDbg()->isTerminator() &&
+            // Don't alter Loop headers and latches to ensure another pass can
+            // detect and transform nested loops later.
+            !LoopHeaders.count(&BB) && !LoopHeaders.count(Succ) &&
+            TryToSimplifyUncondBranchFromEmptyBlock(&BB, DTU)) {
+          RemoveRedundantDbgInstrs(Succ);
+          // BB is valid for cleanup here because we passed in DTU. F remains
+          // BB's parent until a DTU->getDomTree() event.
+          LVI->eraseBlock(&BB);
+          Changed = true;
+        }
       }
     }
     EverChanged |= Changed;
diff --git a/llvm/test/Transforms/JumpThreading/redundant-dbg-info.ll b/llvm/test/Transforms/JumpThreading/redundant-dbg-info.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/redundant-dbg-info.ll
@@ -0,0 +1,78 @@
+; RUN: opt -jump-threading -S < %s | FileCheck %s
+
+define dso_local i32 @_Z3fooi(i32 %a) !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata i32 %a, metadata !12, metadata !DIExpression()), !dbg !13
+  call void @llvm.dbg.value(metadata i32 1, metadata !14, metadata !DIExpression()), !dbg !13
+  %tobool = icmp ne i32 %a, 0, !dbg !15
+  br i1 %tobool, label %if.then, label %if.end, !dbg !17
+
+if.then:                                          ; preds = %entry
+  call void @_Z4callv(), !dbg !18
+  call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression()), !dbg !13
+  br label %if.end, !dbg !20
+
+if.end:                                           ; preds = %if.then, %entry
+  %c.0 = phi i32 [ 0, %if.then ], [ 1, %entry ], !dbg !13
+  call void @llvm.dbg.value(metadata i32 %c.0, metadata !14, metadata !DIExpression()), !dbg !13
+  %tobool1 = icmp ne i32 %c.0, 0, !dbg !21
+  br i1 %tobool1, label %if.else, label %if.then2, !dbg !23
+
+; CHECK-LABEL: if.then2:
+; CHECK: call void @llvm.dbg.value({{.+}}, metadata ![[B:[0-9]+]], metadata !DIExpression())
+; CHECK: call void @llvm.dbg.value({{.+}}, metadata ![[B:[0-9]+]], metadata !DIExpression())
+; CHECK-NOT: call void @llvm.dbg.value({{.+}}, metadata ![[B]], metadata !DIExpression())
+if.then2:                                         ; preds = %if.end
+  call void @llvm.dbg.value(metadata i32 4, metadata !24, metadata !DIExpression()), !dbg !13
+  br label %if.end3, !dbg !25
+
+; CHECK-LABEL: if.end3:
+if.else:                                          ; preds = %if.end
+  call void @llvm.dbg.value(metadata i32 6, metadata !24, metadata !DIExpression()), !dbg !13
+  br label %if.end3
+
+if.end3:                                          ; preds = %if.else, %if.then2
+  %b.0 = phi i32 [ 6, %if.else ], [ 4, %if.then2 ], !dbg !27
+  call void @llvm.dbg.value(metadata i32 %b.0, metadata !24, metadata !DIExpression()), !dbg !13
+  ret i32 %b.0, !dbg !28
+}
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare dso_local void @_Z4callv()
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+; CHECK: ![[B]] = !DILocalVariable(name: "b"
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 10.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0"}
+!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooi", scope: !8, file: !8, line: 3, type: !9, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DIFile(filename: "./test.cpp", directory: "/")
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !8, line: 3, type: !11)
+!13 = !DILocation(line: 0, scope: !7)
+!14 = !DILocalVariable(name: "c", scope: !7, file: !8, line: 4, type: !11)
+!15 = !DILocation(line: 5, column: 7, scope: !16)
+!16 = distinct !DILexicalBlock(scope: !7, file: !8, line: 5, column: 7)
+!17 = !DILocation(line: 5, column: 7, scope: !7)
+!18 = !DILocation(line: 6, column: 5, scope: !19)
+!19 = distinct !DILexicalBlock(scope: !16, file: !8, line: 5, column: 10)
+!20 = !DILocation(line: 8, column: 3, scope: !19)
+!21 = !DILocation(line: 9, column: 8, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !7, file: !8, line: 9, column: 7)
+!23 = !DILocation(line: 9, column: 7, scope: !7)
+!24 = !DILocalVariable(name: "b", scope: !7, file: !8, line: 4, type: !11)
+!25 = !DILocation(line: 11, column: 3, scope: !26)
+!26 = distinct !DILexicalBlock(scope: !22, file: !8, line: 9, column: 11)
+!27 = !DILocation(line: 0, scope: !22)
+!28 = !DILocation(line: 14, column: 3, scope: !7)