diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -1134,13 +1134,13 @@
 
 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
   EventSection = Sections.size();
-  uint32_t Count = readVarint32(Ctx);
+  uint32_t Count = readVaruint32(Ctx);
   Events.reserve(Count);
   while (Count--) {
     wasm::WasmEvent Event;
     Event.Index = NumImportedEvents + Events.size();
     Event.Type.Attribute = readVaruint32(Ctx);
-    Event.Type.SigIndex = readVarint32(Ctx);
+    Event.Type.SigIndex = readVaruint32(Ctx);
     Events.push_back(Event);
   }
 
diff --git a/llvm/test/MC/WebAssembly/event-section-encoding.ll b/llvm/test/MC/WebAssembly/event-section-encoding.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/event-section-encoding.ll
@@ -0,0 +1,345 @@
+; RUN: llc -filetype=obj -exception-model=wasm -mattr=+exception-handling %s -o - | obj2yaml | FileCheck %s
+
+; This is a regression test for an encoding bug that happens when an event's
+; sigindex is greater than 63, so we put 63 dummy functions with different
+; signatures before the function that contains the 'throw' instruction to make
+; the event's sigindex 64.
+
+target triple = "wasm32-unknown-unknown"
+
+declare void @llvm.wasm.throw(i32, i8*)
+
+define i32 @dummy0() {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy1(i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy2(i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy3(i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy4(i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy5(i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy6(i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy7(i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy8(i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy9(i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy10(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy11(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy12(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy13(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy14(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy15(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy16(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy17(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy18(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy19(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy20(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy21(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy22(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy23(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy24(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy25(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy26(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy27(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy28(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy29(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy30(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy31(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy32(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy33(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy34(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy35(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy36(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy37(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy38(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy39(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy40(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy41(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy42(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy43(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy44(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy45(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy46(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy47(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy48(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy49(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy50(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy51(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy52(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy53(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy54(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy55(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy56(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy57(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy58(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy59(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy60(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy61(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy62(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @dummy63(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) {
+entry:
+  ret i32 0
+}
+
+define i32 @test_throw(i8* %p) {
+  call void @llvm.wasm.throw(i32 0, i8* %p)
+  ret i32 0
+}
+
+; Checks to see if the event index is correctly encoded in ULEB128. If it is
+; encoded with LEB128, 64 will not be correctly decoded. 64 is the smallest
+; number with which its LEB128 and ULEB128 encodings are different, because its
+; 7th least significant bit is not 0.
+; CHECK:      - Type:            EVENT
+; CHECK-NEXT:   Events:
+; CHECK-NEXT:     - Index:           0
+; CHECK-NEXT:       Attribute:       0
+; CHECK-NEXT:       SigIndex:        64