diff --git a/llvm/lib/Target/Hexagon/RDFGraph.cpp b/llvm/lib/Target/Hexagon/RDFGraph.cpp
index 156bbda6da73..aebcc22902ad 100644
--- a/llvm/lib/Target/Hexagon/RDFGraph.cpp
+++ b/llvm/lib/Target/Hexagon/RDFGraph.cpp
@@ -1252,7 +1252,7 @@ void DataFlowGraph::buildStmt(NodeAddr<BlockNode*> BA, MachineInstr &In) {
 
   for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
     MachineOperand &Op = In.getOperand(OpN);
-    if (!Op.isReg() || !Op.isUse())
+    if (!Op.isReg() || !Op.isUse() || Op.isUndef())
       continue;
     RegisterRef RR = { Op.getReg(), Op.getSubReg() };
     // Add implicit uses on return and call instructions, and on predicated
diff --git a/llvm/test/CodeGen/Hexagon/rdf-ignore-undef.ll b/llvm/test/CodeGen/Hexagon/rdf-ignore-undef.ll
new file mode 100644
index 000000000000..5d72318f420f
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/rdf-ignore-undef.ll
@@ -0,0 +1,55 @@
+; RUN: llc -march=hexagon -verify-machineinstrs < %s | FileCheck %s
+; Check that we don't crash.
+; CHECK: call foo
+
+target triple = "hexagon"
+
+%struct.1 = type { i16, i8, i32, i8*, i8*, i8*, i8*, i8*, i8*, i32* }
+%struct.0 = type { i32, i32, i32, i32, i32, i32, i32, i32, i32 }
+
+declare void @foo(i8*, %struct.0*) local_unnamed_addr #0
+declare void @bar(%struct.1*, %struct.0* readonly) local_unnamed_addr #0
+
+define i32 @fred(i32 %argc, i8** nocapture readonly %argv) local_unnamed_addr #0 {
+entry:
+  br label %do.body
+
+do.body:                                          ; preds = %if.end88.do.body_crit_edge, %entry
+  %cond = icmp eq i32 undef, 0
+  br i1 %cond, label %if.end49, label %if.then124
+
+if.end49:                                         ; preds = %do.body
+  call void @foo(i8* nonnull undef, %struct.0* nonnull undef) #0
+  br i1 undef, label %if.end55, label %if.then53
+
+if.then53:                                        ; preds = %if.end49
+  call void @bar(%struct.1* null, %struct.0* nonnull undef)
+  br label %if.end55
+
+if.end55:                                         ; preds = %if.then53, %if.end49
+  switch i8 undef, label %sw.epilog79 [
+    i8 0, label %sw.bb77
+    i8 3, label %sw.bb77
+  ]
+
+sw.bb77:                                          ; preds = %if.end55, %if.end55
+  br label %sw.epilog79
+
+sw.epilog79:                                      ; preds = %sw.bb77, %if.end55
+  br i1 undef, label %if.end88, label %if.then81
+
+if.then81:                                        ; preds = %sw.epilog79
+  br label %if.end88
+
+if.end88:                                         ; preds = %if.then81, %sw.epilog79
+  store float 0.000000e+00, float* undef, align 4
+  br i1 undef, label %if.end88.do.body_crit_edge, label %if.then124
+
+if.end88.do.body_crit_edge:                       ; preds = %if.end88
+  br label %do.body
+
+if.then124:                                       ; preds = %if.end88, %do.body
+  unreachable
+}
+
+attributes #0 = { nounwind }