diff --git a/include/llvm/Bitcode/BitstreamReader.h b/include/llvm/Bitcode/BitstreamReader.h
index 865a3e66842..bc3e48a4341 100644
--- a/include/llvm/Bitcode/BitstreamReader.h
+++ b/include/llvm/Bitcode/BitstreamReader.h
@@ -315,7 +315,8 @@ public:
   }
 
   void fillCurWord() {
-    assert(Size == 0 || NextChar < (unsigned)Size);
+    if (Size != 0 && NextChar >= (unsigned)Size)
+      report_fatal_error("Unexpected end of file");
 
     // Read the next word from the stream.
     uint8_t Array[sizeof(word_t)] = {0};
@@ -490,11 +491,11 @@ private:
   //===--------------------------------------------------------------------===//
 
 public:
-
   /// Return the abbreviation for the specified AbbrevId.
   const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
-    unsigned AbbrevNo = AbbrevID-bitc::FIRST_APPLICATION_ABBREV;
-    assert(AbbrevNo < CurAbbrevs.size() && "Invalid abbrev #!");
+    unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
+    if (AbbrevNo >= CurAbbrevs.size())
+      report_fatal_error("Invalid abbrev number");
     return CurAbbrevs[AbbrevNo].get();
   }
 
diff --git a/lib/Bitcode/Reader/BitstreamReader.cpp b/lib/Bitcode/Reader/BitstreamReader.cpp
index 5e3232e5313..9d5fab9147a 100644
--- a/lib/Bitcode/Reader/BitstreamReader.cpp
+++ b/lib/Bitcode/Reader/BitstreamReader.cpp
@@ -170,8 +170,12 @@ unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
   unsigned Code;
   if (CodeOp.isLiteral())
     Code = CodeOp.getLiteralValue();
-  else
+  else {
+    if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
+        CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
+      report_fatal_error("Abbreviation starts with an Array or a Blob");
     Code = readAbbreviatedField(*this, CodeOp);
+  }
 
   for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
     const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
diff --git a/test/Bitcode/Inputs/invalid-abbrev.bc b/test/Bitcode/Inputs/invalid-abbrev.bc
new file mode 100644
index 00000000000..4e8f3944b84
Binary files /dev/null and b/test/Bitcode/Inputs/invalid-abbrev.bc differ
diff --git a/test/Bitcode/Inputs/invalid-bad-abbrev-number.bc b/test/Bitcode/Inputs/invalid-bad-abbrev-number.bc
new file mode 100644
index 00000000000..e4e1fb3e4b3
--- /dev/null
+++ b/test/Bitcode/Inputs/invalid-bad-abbrev-number.bc
@@ -0,0 +1 @@
+BCÀÞ!0000000000
\ No newline at end of file
diff --git a/test/Bitcode/Inputs/invalid-unexpected-eof.bc b/test/Bitcode/Inputs/invalid-unexpected-eof.bc
new file mode 100644
index 00000000000..a487393d066
--- /dev/null
+++ b/test/Bitcode/Inputs/invalid-unexpected-eof.bc
@@ -0,0 +1 @@
+BCÀÞ!00000000000000000000
\ No newline at end of file
diff --git a/test/Bitcode/invalid.test b/test/Bitcode/invalid.test
index 5f88da45f6a..19ef3267cc6 100644
--- a/test/Bitcode/invalid.test
+++ b/test/Bitcode/invalid.test
@@ -1 +1,13 @@
-RUN: not llvm-dis -disable-output %p/Inputs/invalid-pr20485.bc
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-pr20485.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INVALID-ENCODING %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-abbrev.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=BAD-ABBREV %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-unexpected-eof.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=UNEXPECTED-EOF %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-bad-abbrev-number.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=BAD-ABBREV-NUMBER %s
+
+INVALID-ENCODING: Invalid encoding
+BAD-ABBREV: Abbreviation starts with an Array or a Blob
+UNEXPECTED-EOF: Unexpected end of file
+BAD-ABBREV-NUMBER: Invalid abbrev number