diff --git a/indra/llmessage/aicurl.cpp b/indra/llmessage/aicurl.cpp
index c68399059..6d3cbf4b0 100644
--- a/indra/llmessage/aicurl.cpp
+++ b/indra/llmessage/aicurl.cpp
@@ -1191,9 +1191,7 @@ void CurlResponderBuffer::resetState(AICurlEasyRequest_wat& curl_easy_request_w)
   curl_easy_request_w->resetState();
 
   mOutput.reset();
-  
-  mInput.str("");
-  mInput.clear();
+  mInput.reset();
   
   mHeaderOutput.str("");
   mHeaderOutput.clear();
@@ -1211,6 +1209,10 @@ void CurlResponderBuffer::prepRequest(AICurlEasyRequest_wat& curl_easy_request_w
 	curl_easy_request_w->setoptString(CURLOPT_ENCODING, "");
   }
 
+  mInput.reset(new LLBufferArray);
+  mInput->setThreaded(true);
+  mLastRead = NULL;
+
   mOutput.reset(new LLBufferArray);
   mOutput->setThreaded(true);
 
@@ -1271,16 +1273,10 @@ size_t CurlResponderBuffer::curlReadCallback(char* data, size_t size, size_t nme
   // to make sure that callbacks and destruction aren't done simultaneously.
   AICurlEasyRequest_wat buffered_easy_request_w(*lockobj);
 
+  S32 bytes = size * nmemb;		// The maximum amount to read.
   AICurlResponderBuffer_wat buffer_w(*lockobj);
-  S32 n = size * nmemb;
-  S32 startpos = buffer_w->getInput().tellg();
-  buffer_w->getInput().seekg(0, std::ios::end);
-  S32 endpos = buffer_w->getInput().tellg();
-  buffer_w->getInput().seekg(startpos, std::ios::beg);
-  S32 maxn = endpos - startpos;
-  n = llmin(n, maxn);
-  buffer_w->getInput().read(data, n);
-  return n;
+  buffer_w->mLastRead = buffer_w->getInput()->readAfter(sChannels.out(), buffer_w->mLastRead, (U8*)data, bytes);
+  return bytes;					// Return the amount actually read.
 }
 
 //static
diff --git a/indra/llmessage/aicurlprivate.h b/indra/llmessage/aicurlprivate.h
index 38ce00b5c..14a8b0fa2 100644
--- a/indra/llmessage/aicurlprivate.h
+++ b/indra/llmessage/aicurlprivate.h
@@ -291,9 +291,9 @@ class CurlResponderBuffer : protected AICurlEasyHandleEvents {
 	void resetState(AICurlEasyRequest_wat& curl_easy_request_w);
 	void prepRequest(AICurlEasyRequest_wat& buffered_curl_easy_request_w, std::vector<std::string> const& headers, AICurlInterface::ResponderPtr responder, S32 time_out = 0, bool post = false);
 
-	std::stringstream& getInput() { return mInput; }
-	std::stringstream& getHeaderOutput() { return mHeaderOutput; }
-	LLIOPipe::buffer_ptr_t& getOutput() { return mOutput; }
+	LLIOPipe::buffer_ptr_t& getInput(void) { return mInput; }
+	std::stringstream& getHeaderOutput(void) { return mHeaderOutput; }
+	LLIOPipe::buffer_ptr_t& getOutput(void) { return mOutput; }
 
 	// Called if libcurl doesn't deliver within CurlRequestTimeOut seconds.
 	void timed_out(void);
@@ -307,13 +307,14 @@ class CurlResponderBuffer : protected AICurlEasyHandleEvents {
 	/*virtual*/ void removed_from_multi_handle(AICurlEasyRequest_wat& curl_easy_request_w);
 
   private:
-	std::stringstream mInput;
+	LLIOPipe::buffer_ptr_t mInput;
+	U8* mLastRead;										// Pointer into mInput where we last stopped reading (or NULL to start at the beginning).
 	std::stringstream mHeaderOutput;
 	LLIOPipe::buffer_ptr_t mOutput;
 	AICurlInterface::ResponderPtr mResponder;
 
   public:
-	static LLChannelDescriptors const sChannels;		// Channel object for mOutput: we ONLY use channel 0, so this can be a constant.
+	static LLChannelDescriptors const sChannels;		// Channel object for mInput (channel out()) and mOutput (channel in()).
 
   private:
 	// This class may only be created by constructing a ThreadSafeBufferedCurlEasyRequest.
diff --git a/indra/newview/llcurlrequest.cpp b/indra/newview/llcurlrequest.cpp
index e50bd040e..0c566fed2 100644
--- a/indra/newview/llcurlrequest.cpp
+++ b/indra/newview/llcurlrequest.cpp
@@ -41,6 +41,8 @@
 
 #include "llsdserialize.h"
 #include "llcurlrequest.h"
+#include "llbuffer.h"
+#include "llbufferstream.h"
 #include "statemachine/aicurleasyrequeststatemachine.h"
 
 //-----------------------------------------------------------------------------
@@ -94,8 +96,11 @@ bool Request::post(std::string const& url, headers_t const& headers, std::string
 
 	buffer_w->prepRequest(buffered_easy_request_w, headers, responder);
 
-	buffer_w->getInput().write(data.data(), data.size());
-	S32 bytes = buffer_w->getInput().str().length();
+	U32 bytes = data.size();
+	bool success = buffer_w->getInput()->append(buffer_w->sChannels.out(), (U8 const*)data.data(), bytes);
+	llassert_always(success);	// AIFIXME: Maybe throw an error.
+	if (!success)
+	  return false;
 	buffered_easy_request_w->setPost(NULL, bytes);
 	buffered_easy_request_w->addHeader("Content-Type: application/octet-stream");
 	buffered_easy_request_w->finalizeRequest(url);
@@ -121,8 +126,9 @@ bool Request::post(std::string const& url, headers_t const& headers, LLSD const&
 
 	buffer_w->prepRequest(buffered_easy_request_w, headers, responder);
 
-	LLSDSerialize::toXML(data, buffer_w->getInput());
-	S32 bytes = buffer_w->getInput().str().length();
+	LLBufferStream buffer_stream(buffer_w->sChannels, buffer_w->getInput().get());
+	LLSDSerialize::toXML(data, buffer_stream);
+	S32 bytes = buffer_w->getInput()->countAfter(buffer_w->sChannels.out(), NULL);
 	buffered_easy_request_w->setPost(NULL, bytes);
 	buffered_easy_request_w->addHeader("Content-Type: application/llsd+xml");
 	buffered_easy_request_w->finalizeRequest(url);