diff --git a/lib/SPIRV/libSPIRV/SPIRVModule.cpp b/lib/SPIRV/libSPIRV/SPIRVModule.cpp
index c07d5c1ac9..064076d1fe 100644
--- a/lib/SPIRV/libSPIRV/SPIRVModule.cpp
+++ b/lib/SPIRV/libSPIRV/SPIRVModule.cpp
@@ -2623,7 +2623,8 @@ std::istream &SPIRVModuleImpl::parseSPIRV(std::istream &I) {
   MI.setAutoAddExtensions(false);
 
   SPIRVWord Header[5] = {0};
-  I.read(reinterpret_cast<char *>(&Header), sizeof(Header));
+  for (auto &H : Header)
+    H = readSPIRVWord(I);
 
   SPIRVErrorLog &ErrorLog = MI.getErrorLog();
   if (!ErrorLog.checkError(!I.eof(), SPIRVEC_InvalidModule,
@@ -2660,8 +2661,7 @@ std::istream &SPIRVModuleImpl::parseSPIRV(std::istream &I) {
 
   SPIRVEntry *Scope = nullptr;
   while (true) {
-    SPIRVWord WordCountAndOpCode = 0;
-    I.read(reinterpret_cast<char *>(&WordCountAndOpCode), sizeof(SPIRVWord));
+    SPIRVWord WordCountAndOpCode = readSPIRVWord(I);
     SPIRVDBG(spvdbgs() << "Read word: W = " << WordCountAndOpCode
                        << " V = 0\n");
     SPIRVWord WordCount = WordCountAndOpCode >> 16;
@@ -2784,8 +2784,8 @@ SPIRVId SPIRVModuleImpl::getExtInstSetId(SPIRVExtInstSetKind Kind) const {
 bool isSpirvBinary(const std::string &Img) {
   if (Img.size() < sizeof(unsigned))
     return false;
-  const auto *Magic = reinterpret_cast<const unsigned *>(Img.data());
-  return *Magic == MagicNumber;
+  std::istringstream IS(Img);
+  return readSPIRVWord(IS) == MagicNumber;
 }
 
 #ifdef _SPIRV_SUPPORT_TEXT_FMT
diff --git a/lib/SPIRV/libSPIRV/SPIRVStream.h b/lib/SPIRV/libSPIRV/SPIRVStream.h
index 21cb51a3a0..68df75e3e7 100644
--- a/lib/SPIRV/libSPIRV/SPIRVStream.h
+++ b/lib/SPIRV/libSPIRV/SPIRVStream.h
@@ -98,10 +98,20 @@ class SPIRVNL {
   friend spv_ostream &operator<<(spv_ostream &O, const SPIRVNL &E);
 };
 
+/// Read a single SPIR-V word from a binary stream, byte-swapping from
+/// little-endian on big-endian hosts.
+inline uint32_t readSPIRVWord(std::istream &IS) {
+  uint32_t W;
+  IS.read(reinterpret_cast<char *>(&W), sizeof(W));
+#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+  W = __builtin_bswap32(W);
+#endif
+  return W;
+}
+
 template <typename T>
 const SPIRVDecoder &decodeBinary(const SPIRVDecoder &I, T &V) {
-  uint32_t W;
-  I.IS.read(reinterpret_cast<char *>(&W), sizeof(W));
+  uint32_t W = readSPIRVWord(I.IS);
   V = static_cast<T>(W);
   SPIRVDBG(spvdbgs() << "Read word: W = " << W << " V = " << V << '\n');
   return I;
@@ -186,6 +196,10 @@ const SPIRVEncoder &operator<<(const SPIRVEncoder &O, T V) {
   }
 #endif
   uint32_t W = static_cast<uint32_t>(V);
+#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+  // SPIR-V binary format is little-endian; byte-swap on big-endian hosts.
+  W = __builtin_bswap32(W);
+#endif
   O.OS.write(reinterpret_cast<char *>(&W), sizeof(W));
   return O;
 }