diff --git a/src/s_advsound.cpp b/src/s_advsound.cpp
index 7f9cd8592e..e121bc2ee1 100644
--- a/src/s_advsound.cpp
+++ b/src/s_advsound.cpp
@@ -1772,6 +1772,100 @@ int S_FindSkinnedSoundEx (AActor *actor, const char *name, const char *extendedn
 	return S_FindSkinnedSound (actor, id);
 }
 
+//==========================================================================
+//
+// S_ParseTimeTag
+//
+// Passed the value of a loop point tag, converts it to numbers.
+//
+// This may be of the form 00:00:00.00 (HH:MM:SS.ss) to specify by play
+// time. Various parts may be left off. The only requirement is that it
+// contain a colon. e.g. To start the loop at 20 seconds in, you can use
+// ":20", "0:20", "00:00:20", ":20.0", etc. Values after the decimal are
+// fractions of a second.
+//
+// If you don't include a colon but just have a raw number, then it's
+// the number of PCM samples at which to loop.
+//
+// Returns true if the tag made sense, false if not.
+//
+//==========================================================================
+
+bool S_ParseTimeTag(const char *tag, bool *as_samples, unsigned int *time)
+{
+	const char *bit = tag;
+	char ms[3] = { 0 };
+	unsigned int times[3] = { 0 };
+	int ms_pos = 0, time_pos = 0;
+	bool pcm = true, in_ms = false;
+
+	for (bit = tag; *bit != '\0'; ++bit)
+	{
+		if (*bit >= '0' && *bit <= '9')
+		{
+			if (in_ms)
+			{
+				// Ignore anything past three fractional digits.
+				if (ms_pos < 3)
+				{
+					ms[ms_pos++] = *bit - '0';
+				}
+			}
+			else
+			{
+				times[time_pos] = times[time_pos] * 10 + *bit - '0';
+			}
+		}
+		else if (*bit == ':')
+		{
+			if (in_ms)
+			{ // If we already specified milliseconds, we can't take any more parts.
+				return false;
+			}
+			pcm = false;
+			if (++time_pos == countof(times))
+			{ // Time too long. (Seriously, starting the loop days in?)
+				return false;
+			}
+		}
+		else if (*bit == '.')
+		{
+			if (pcm || in_ms)
+			{ // It doesn't make sense to have fractional PCM values.
+			  // It also doesn't make sense to have more than one dot.
+				return false;
+			}
+			in_ms = true;
+		}
+		else
+		{ // Anything else: We don't understand this.
+			return false;
+		}
+	}
+	if (pcm)
+	{
+		*as_samples = true;
+		*time = times[0];
+	}
+	else
+	{
+		unsigned int mytime = 0;
+
+		// Add in hours, minutes, and seconds
+		for (int i = 0; i <= time_pos; ++i)
+		{
+			mytime = mytime * 60 + times[i];
+		}
+
+		// Add in milliseconds
+		mytime = mytime * 1000 + ms[0] * 100 + ms[1] * 10 + ms[2];
+
+		*as_samples = false;
+		*time = mytime;
+	}
+	return true;
+}
+
 //==========================================================================
 //
 // CCMD soundlist
diff --git a/src/s_sound.h b/src/s_sound.h
index 41820bec78..8d89d1a0de 100644
--- a/src/s_sound.h
+++ b/src/s_sound.h
@@ -354,6 +354,7 @@ void S_UnloadSound (sfxinfo_t *sfx);
 sfxinfo_t *S_LoadSound(sfxinfo_t *sfx);
 unsigned int S_GetMSLength(FSoundID sound);
 void S_ParseMusInfo();
+bool S_ParseTimeTag(const char *tag, bool *as_samples, unsigned int *time);
 
 // [RH] Prints sound debug info to the screen.
 //		Modelled after Hexen's noise cheat.
diff --git a/src/sound/fmodsound.cpp b/src/sound/fmodsound.cpp
index e167d389f8..e94ec04b7d 100644
--- a/src/sound/fmodsound.cpp
+++ b/src/sound/fmodsound.cpp
@@ -61,6 +61,7 @@ extern HWND Window;
 #include "v_video.h"
 #include "v_palette.h"
 #include "cmdlib.h"
+#include "s_sound.h"
 
 // MACROS ------------------------------------------------------------------
 
@@ -1435,6 +1436,26 @@ SoundStream *FMODSoundRenderer::CreateStream (SoundStreamCallback callback, int
 	return capsule;
 }
 
+//==========================================================================
+//
+// GetTagData
+//
+// Checks for a string-type tag, and returns its data.
+//
+//==========================================================================
+
+const char *GetTagData(FMOD::Sound *sound, const char *tag_name)
+{
+	FMOD_TAG tag;
+
+	if (FMOD_OK == sound->getTag(tag_name, 0, &tag) &&
+		(tag.datatype == FMOD_TAGDATATYPE_STRING || tag.datatype == FMOD_TAGDATATYPE_STRING_UTF8))
+	{
+		return (const char *)tag.data;
+	}
+	return NULL;
+}
+
 //==========================================================================
 //
 // FMODSoundRenderer :: OpenStream
@@ -1496,6 +1517,61 @@ SoundStream *FMODSoundRenderer::OpenStream(const char *filename_or_data, int fla
 	}
 	if (result == FMOD_OK)
 	{
+		// Handle custom loop starts by checking for a "loop_start" tag.
+#if 0
+		FMOD_TAG tag;
+		int numtags;
+		if (FMOD_OK == stream->getNumTags(&numtags, NULL))
+		{
+			for (int i = 0; i < numtags; ++i)
+			{
+				if (FMOD_OK == stream->getTag(NULL, i, &tag))
+				{
+					Printf("Tag %2d. %d %s = %s\n", i, tag.datatype, tag.name, tag.data);
+				}
+			}
+		}
+#endif
+		const char *tag_data;
+		unsigned int looppt[2];
+		bool looppt_as_samples[2], have_looppt[2] = { false };
+		static const char *const loop_tags[2] = { "LOOP_START", "LOOP_END" };
+
+		for (int i = 0; i < 2; ++i)
+		{
+			if (NULL != (tag_data = GetTagData(stream, loop_tags[i])))
+			{
+				if (S_ParseTimeTag(tag_data, &looppt_as_samples[i], &looppt[i]))
+				{
+					have_looppt[i] = true;
+				}
+				else
+				{
+					Printf("Invalid %s tag: '%s'\n", loop_tags[i], tag_data);
+				}
+			}
+		}
+		if (have_looppt[0] && !have_looppt[1])
+		{ // Have a start tag, but not an end tag: End at the end of the song.
+			have_looppt[1] = (FMOD_OK == stream->getLength(&looppt[1], FMOD_TIMEUNIT_PCM));
+			looppt_as_samples[1] = true;
+		}
+		else if (!have_looppt[0] && have_looppt[1])
+		{ // Have an end tag, but no start tag: Start at beginning of the song.
+			looppt[0] = 0;
+			looppt_as_samples[0] = true;
+			have_looppt[0] = true;
+		}
+		if (have_looppt[0] && have_looppt[1])
+		{ // Have both loop points: Try to set the loop.
+			FMOD_RESULT res = stream->setLoopPoints(
+				looppt[0], looppt_as_samples[0] ? FMOD_TIMEUNIT_PCM : FMOD_TIMEUNIT_MS,
+				looppt[1] - 1, looppt_as_samples[1] ? FMOD_TIMEUNIT_PCM : FMOD_TIMEUNIT_MS);
+			if (res != FMOD_OK)
+			{
+				Printf("Setting custom song loop points for song failed. Error %d\n", res);
+			}
+		}
 		return new FMODStreamCapsule(stream, this, url ? filename_or_data : NULL);
 	}
 	return NULL;