diff --git a/llvm/include/llvm/Support/ErrorHandling.h b/llvm/include/llvm/Support/ErrorHandling.h
--- a/llvm/include/llvm/Support/ErrorHandling.h
+++ b/llvm/include/llvm/Support/ErrorHandling.h
@@ -110,9 +110,9 @@
 /// the following unwind succeeds, e.g. do not trigger additional allocations
 /// in the unwind chain.
 ///
-/// If no error handler is installed (default), then a bad_alloc exception
-/// is thrown, if LLVM is compiled with exception support, otherwise an
-/// assertion is called.
+/// If no error handler is installed (default), throws a bad_alloc exception
+/// if LLVM is compiled with exception support. Otherwise prints the error
+/// to standard error and calls abort().
 LLVM_ATTRIBUTE_NORETURN void report_bad_alloc_error(const char *Reason,
                                                     bool GenCrashDiag = true);
 
diff --git a/llvm/lib/Support/ErrorHandling.cpp b/llvm/lib/Support/ErrorHandling.cpp
--- a/llvm/lib/Support/ErrorHandling.cpp
+++ b/llvm/lib/Support/ErrorHandling.cpp
@@ -170,6 +170,7 @@
   // an OOM to stderr and abort.
   char OOMMessage[] = "LLVM ERROR: out of memory\n";
   ssize_t written = ::write(2, OOMMessage, strlen(OOMMessage));
+  written = ::write(2, Reason, strlen(Reason));
   (void)written;
   abort();
 #endif
diff --git a/llvm/lib/Support/SmallVector.cpp b/llvm/lib/Support/SmallVector.cpp
--- a/llvm/lib/Support/SmallVector.cpp
+++ b/llvm/lib/Support/SmallVector.cpp
@@ -49,14 +49,19 @@
   // Ensure we can fit the new capacity.
   // This is only going to be applicable when the capacity is 32 bit.
   if (MinCapacity > SizeTypeMax())
-    report_bad_alloc_error("SmallVector capacity overflow during allocation");
+    report_fatal_error("SmallVector unable to grow. Requested capacity (" +
+                       std::to_string(MinCapacity) +
+                       ") is larger than maximum capacity for size type (" +
+                       std::to_string(SizeTypeMax()) + ")");
 
   // Ensure we can meet the guarantee of space for at least one more element.
   // The above check alone will not catch the case where grow is called with a
   // default MinCapacity of 0, but the current capacity cannot be increased.
   // This is only going to be applicable when the capacity is 32 bit.
   if (capacity() == SizeTypeMax())
-    report_bad_alloc_error("SmallVector capacity unable to grow");
+    report_fatal_error(
+        "SmallVector capacity unable to grow. Already at maximum size " +
+        std::to_string(SizeTypeMax()));
 
   // In theory 2*capacity can overflow if the capacity is 64 bit, but the
   // original capacity would never be large enough for this to be a problem.