1 files changed, 5 insertions, 1 deletions
diff --git a/src/librustc_codegen_llvm/llvm_util.rs b/src/librustc_codegen_llvm/llvm_util.rs
index 2dce9b04c9e..a56d015a1b2 100644
--- a/src/librustc_codegen_llvm/llvm_util.rs
+++ b/src/librustc_codegen_llvm/llvm_util.rs
@@ -3,7 +3,7 @@ use crate::llvm;
 use syntax_pos::symbol::Symbol;
 use rustc::session::Session;
 use rustc::session::config::PrintRequest;
-use rustc_target::spec::MergeFunctions;
+use rustc_target::spec::{MergeFunctions, PanicStrategy};
 use libc::c_int;
 use std::ffi::CString;
 use syntax::feature_gate::UnstableFeatures;
@@ -73,6 +73,10 @@ unsafe fn configure_llvm(sess: &Session) {
             }
         }
 
+        if sess.target.target.target_os == "emscripten" && sess.panic_strategy() == PanicStrategy::Unwind {
+            add("-enable-emscripten-cxx-exceptions");
+        }
+
         // HACK(eddyb) LLVM inserts `llvm.assume` calls to preserve align attributes
         // during inlining. Unfortunately these may block other optimizations.
         add("-preserve-alignment-assumptions-during-inlining=false");